My '84 B2000 decided to crap out yesterday. I was driving along and it quit pulling and idling rough. As soon as I give it gas, it tries to die. I can't find any vacuum leaks, and the float bowl is staying full. After tinkering for an hour, it started up and ran fine. I gave it some gas and it was fine, then all of sudden, I hit the gas again and it started the same symptoms once more. Any ideas?

 

by the fuel bowl staying full do you mean its overfilling
if so the needle and seat on the float is dirty and not sealing when the bowl is full
this would allow it to overfill and almost or completely flood the engine with gas

 

No, it's staying just above the level line (where it is always maintained since I have owned it).

 

no vacuum leaks at the base of the carb

i've used a propane torch to check for leaks
but you could use carb cleaner or wd-40
the leak will suck it in and seal for a bit
might help in finding

with the engine off try looking in the carb and operate the throttle and see if the accelerater pump squirts an extra shot of fuel (needed to accel) for the extra air coming in