Won't idle/leaning out

[Alisha]

Hi, I'm hoping someone here can help....

We have a 347 with fuel injection. We've always had problems with the car leaning out. We had a chip made for the computer (was told in the beginning our computer would adjust to the engine...it didn't) which seemed to help but according to the guy who built our engine, it's still not enough...the car still needs more gas. We were using 36 lb injectors with a 70mm mass air meter (maybe 75...can't remember but it did match the injector size) ...he suggested we go up to 42 lb injectors to get more fuel which would also mean we needed an 81 mm mass air meter. We went to order both parts, we explained what the car was doing and was told it wouldn't make sense to change the injectors and the mass air meter. Said if we needed more gas and less air then we shouldn't change the mass air meter...or to at least try the larger injectors first.

We've installed the larger injectors and it is running much more rich. Now it won't idle correctly at all...

That's another problem we've had as well from the beginning...the car "surges" (I think that's what it was called). Before the larger injectors the car wouldn't idle correctly when in drive but if in park it was fine. The idle would jump up and down when in drive...like it didn't know where it should be causing the car to rock back and forth. Now with the larger injectors it's much worse. When first started it idles at 1000 but after about a minute it drops to 500 then jumps to around 1300+. It'll jump up and down 5-6 times then die. When in drive it won't hold an idle at all...you have to constantly give it gas to keep it running.

Any ideas?