Right away this morning things were wierd.  She started fine, but when she was cold if I pressed the gas pedal the engine would almost die, like a cold outboard boat motor this is too cold. I had to sit in the driveway and slowly add throttle to shake out the cobwebs.  This hasn't happened any other morning?  This morning might have been a little cooler but not much.  Once she warmed up, it was much better, but would still happen at higher rpm or under load.

I drove all the way to work but was really worried, anytime the freeway started to incline I would get random coughing "popping" stumbling.

It is worst when she is cold, after work when I started her back up I could hardly go up a small incline with the engine coughing/stumbing and backfiring out the exhaust.  But as she warms up it gets better, but still happens when I get on the gas going up even a small hill or if I get too high in the rpms it'll happen.  If I don't use too much throttle I can avoid it.

But somethign has definitly changed, the first few days of driving her I was LOVING the low rpm torque, but now if I get too low in the rpms and then give throttle she submbles and backfires out the exhaust.

Should I be looking at the distributor?

This changed so fast  - it seems like it must be a carb problem. A good cleaning with spray carb cleaner might be in order.

You just worked over the tank and fuel line correct? Is there a filter in the line to the carb now?

Sounds like the last time I left my manual choke on and didn't realize it. Check your choke for binding. Probably cold enough to get to a place where it hasn't been for a while.

Cheers

Warren 

This is a long shot.  In the process of getting it running, did you put new points in, I don't remember?  If so, did you put any lube on the cam/rubbing block?  If not, it is possible that the rubbing block has worn prematurely and the point gap is closed up.  Take a look at the point gap.

Here are some answers to your questions:

1) Gas is less than a week old

2) Carb is freshly rebuilt, I don't have any additional filter on the fuel line

3) Choke does open once car warms up, I haven't checked to see that it starts closed, but I assume so since the car starts well

4) Car starts perfectly, one push of the pedal, turn the key and VROOOM..she roars to life.

5) This problem, although it improves after car warms up, still exists well after I'm at operating temperature, it is just a higher rpm or under load

6) I tried to check timing, but my balancer doesn't have any timing marks anymore, just solid rust

7) I have done nothing with the distributor, it is the original distributor I assume.  Getting into points and stuff is a new frontier for me

8) Forgot to add (thanks moonshadow for reminder), the fuel system is completely new, The only part of the fuel system that isn't new is the pump itself and the hard line from the pump to the carb.

Went home over lunch (it is 60 degrees F).  Removed the air cleaner so I could watch what happens.  When I pumped the pedal once before starting the choke closed appropriately.  When I turned the key the car started immediately, but then quickly died!

In my initial post I forgot to mention this as one of the new symptoms.  It doesn't stay running if I start from cold.  Up until yesterday morning If I pumped the pedal once, and turned the key, the car would start right up and stay at high idle.  I could drive away even before the car warmed up without problem.  Yesterday morning was the first time it died right after starting.

Now when I start it cold, if I don't give it some gas it dies in a few seconds. However if I push the gas pedal too much it also stumbles and dies.  I have to very carefully feather throttle and slowly apply more throttle to get it to warm up.

I think all of you who pointed to the carb are right, something happened and it is running lean.  It seems when I'm starting from cold, the squirt of gas from the accelerator pump is enough to get the engine to start, but once that is used up the carb is running too lean to stary running even when the choke is applied.

How could this happen overnight?  Does this mean I likely have a piece of debri that found it's way into my carb?  What part of the carb should I open and where should I look first?  Since I have the old fuel pump it is possible some old gas goo was in there and it worked its way up into my  newly rebuild carb.

What dizzy are you running? Is it the original advance-o-matic with vacuum advance only? I had problems like you describe when I tore a hole in the diaphragm. One backfire is all it takes. Check it by disconnecting it and sucking on the pipe (or you can use some hose) if you can suck air it's stuffed.

You need a filter, I run two. I use a Fram HPG1 at the rear just forward of the left rear wheel with the bracket bolted to the frame rail. Then another generic filter between the fuel pump and the carb. The only way you can be sure that a fuel system is clear of muck is to replace everything. Then it's only good until you put fuel in it. I don't expect that I'll be replacing the one between the pump and the carb too often because of blockage but then again I don't expect to get much muck in my carb either.

The other obvious is the fuel pump (if your carb is rebuilt and clean) connect you carb to another fuel source. Fuel bottle, hose and gravity feed to the carb. then start you engine and have your pump pump fuel into another container. Eratic, poor flow, no fuel will indicate a problem. Racers use this method with a stop watch and measure the fuel over the tested time to calculate tier requirements. Take precautions to avoid fire. Ensure fuel containers are large enough, use assistance and have a firer extinguisher handy.   

cheers

Warren     

When you do have to look for a fuel pump - do you have room under it for the FE truck style canister fuel filter? If so, go that way, makes future service way easier (and not much if any additional cost).

I've had two pumps that failed and the car still ran (just). one had the pivot of the pump arm wriggle out of position which mean that the pump often pumped normal and ran fine then disengaged & left the engine run out of fuel.

The other the the valves were about to go and would provide sufficient fuel at idle but insufficient for road speed.

I have recently installed a FE fuel pump on my Y. I thought my pump was fine but was worried because of it's age that it would leave me somewhere. I have installed electric wipers and have no need for vacuum I got an improvement across the board even at idle.

There's a lot to be said for getting enough fuel at the right pressure.

cheers

Warren

Just to be safe I dumped in a can of fuel system cleaner into the tank.  I should probably get a fuel filter in line before the carb soon too.

Have you a fuel filter in your fuel system yet? Fixing the symptom will never fix the cause.

cheers

Warren