1979 f150. 351m my 2 barrel carb. Spits and pops when I press the gas pedal and the truck tries to di3

Could be the carb but also sounds like it could be a timing chain problem to, It could be stretched enough where its firing on the intake stroke causing it to pop up through the carb..

Your 79 351 was not designed to run on ethanol blended fuel much less 87 octane fuel. First, the ethanol in the fuel is basically going to deteriorate any gasket or rubber fitting it touches, over time. This could result in a vacuum leak causing the problem. Try running a few gallons of non-ethanol fuel through it and see if it helps a little. If you cannot find non- ethanol fuel in your area, check out any boat launch which sells fuel. Outboard motors and marine engines operate only on non ethanol fuel.

I have replaced old carb with a 4 barrel holly 600. The accelerator pump was bad in the old 2 barel. doesn't spit and pop but is still doing the same thing just not as bad. U can only press the throttle a little bit. Too much and it hesitates or lags. Like its being starved for fuel. I have removed all emission stuff and have no vacuum leaks. Is the only vacuum needed to run properly the timing advance? That is the only vacuum ran to the carb. The choke is electric. Also have good plugs and a new coil.

check the timing chain for excesive play