ok here go i need help, 91 chevy 1500 pickup had 350, removed installed 305 used intake,tbi,exhaust,from 350 bought all new sensors for 305 engine runs great at high rpms but will not idle have check for intake & tbi leak can not find one also have new plugs, wires,cap,rotor,timing chain&gears timing is set
engine is suppose to have a mild cam in it sounds like it dose anyway,
Help!!!!!!! please i'm about to go crazy over this truck.

 

did u swap ecms? also the 350 tbi injectors will run u rich unless you tune.

 

See the sticky post on the 305 -> 350 swap. You should be able to reverse all that info for your 350 to 305 swap.

My concern is the "mild cam" you mentioned. You can't run an aftermarket cam with TBI and expect any improvements (without proper tuning). In some cases it'll run worse. I would try to really figure out what cam we are working with here. If it's not stock, it should be really cheap to find a stock cam.

Also see the tech articles on timing adjustments and IAC cleaning.