1971 f250 will not stay running

[christopher1970]

This is my first post so bare with me.I have a 1971 f250 with a 390 and a 2 barrell carb.
Problem is i went to start it and had to keep pumping gas pedal to get it to start once started it would run but i had to keep foot on gas as soon as i let up on gas it started bogging and would die.
Got it started and put it in drive and it ran fine 30 miles on fwy but as soon as i got off fwy and would let up on gas it started dying finally came to red light and it just died.
ran great and started fine an hour before
any help with this would be appreciated

[Manny]

Several things to look at here in my opinion. Sounds like you may have a vacuum leak issue first off, but could also be other. I would say you are leaking vacuum around the engine possibly carb or something. First will be to raise the idle up to see if the truck will run at all at an idle. What specs are you 390 still stock with 2 bbl aftermarket carb or anything. This will help get you to the right spot. The idle screw will be near the throttle arm on the carb and by twisting it with a screwdriver may cause you engine to idle properly. If this does not cure the issue then you may at least get it to idle long enough to be able to look around for a vacuum leak and troubleshoot. Listen under hood for any hissing sounds from air being sucked into a spot it should not be like a missing plug or cracked rubber hose ( does not hurt to check them all from the get go) Finally the pumping the gas issues to start just seems like the is not working causing the engine to be a little cold natured as most of these old trucks are. Let me know what you find there and touch back in with us.