need some engine help! 86. 350

[penaduny]

heres my problem. my truck will idle fine, rev fine. nothing out of the ordinary. if i go do drive it around, after about a half a mile, i get horrible hesitation, thing almost dies, if i get on it, it will die, and my brakes really dont work at all. so i came to the conclusion of a vacuum problem.. so i changed a bunch of vacuum lines, put a new brake booster in for the hell of it, checked everything else i could. and nothing has changed. the truck pretty much started doing this out of nowhere. i put a new motor/trany in about a year ago, had the carb rebuit at the same time. so now i take it to my freinds shop to see if they can find out whats wrong. they said it was the carb. so i got it home. took the carb off and brought it to the place i had reuild it, they checked it all out, hooked it up to this motor they have on a dyno, and everything checked out perfectly fine. so im stumped. put the carb back on. double check everything, every vacuum line. truck starts right up. but still. same thing.

more backround: this has all the cali emissions bull**** on the motor. when i put the new 350 in i put almost all new parts on.

anybody have some sugestions for me?

any help would be greatly appreciated.