I just picked upa 88 B2200 5sp with 200,000 miles on it for a commuter. It seems to run good, but occasionaly dies after cruise /accell then depressing the clutch (idling). The temp gauge does not work, but it smelled hot so I lifted the hood after a 12 mile drive home and noticed the exhaust manifold was hot enough to glow bright orange, and the idle was too high. This all sounds like a lean condition caused by vacuum leak, but I could not find one with the use of brake clean or stuffing a rag over vacuum leak prone areas.

Does anyone have any ideas where to start looking for this. It is all original, the vacuum lines are all there and look to be placed properly, but I have not traced them yet.

 

there are two vaccume lines that run under the intake manifold right behind the carb mine came loose and truck did the same as yours....