Hello.



New member here with a problem.



I have a 292 motor in a 56 Ford truck that starts right up ,idles fine ,runs around the neihborhood

with no problem....but when I get out on the highway and put it in 4th gear it "breaks up" and wants to shut down...



I have replaced...



all 8 plugs

distributor cap

rotor

points

condenser

coil



I run a mechanical fuel pump that was also recently replaced.



Im just out of ideas and looking for some input as to where to look next.



I have owned the truck for 8 years and this problem started last year on a short trip

I never addressed it because most of the time the truck is transported on a trailer...but I would like to get it fixed if I could.....Thanks in advance for any help .



Bob Taylor