i cant figure it out.

i just bought a 89 gta with a l98, the car was running fine when it had lt1 injectors @ 58 psi, other than the fact it was running rich and sometimes the injectors didn't want to work. then i swapped to some bosch 3 #22 injectors and tuned the fuel pressure to 44psi.

problem is right at start up the car stumbles and sounds like it is about to die but if i burp the thottle it with smoothen out and run fine. untill i try to drive it. i will put it in gear and it hesitates bad when i give it some gas, but about 2 minutes later with will have problems and will run great.

i figured it could be a little lean so i bumped the fuel up to 50 psi and had the same problem. timing is at 6* BTDC, and it's a pretty stock engine, just has siamised plenum and thats about it.

any ideas?

 

Well hesitation issures are usually caused by a lean mixture or a timing probem. Check the car for vacuum leaks and also pull a few spark plugs and see what color they are.