Well, I finally finished the swap about three weeks ago and have been running into trouble, i have been trying my hardest to figure them out myself.... Now i need your help. Heres a little background information on my project. My motor already had tbi heads on it for the future swap. Old block, with tbi heads. THe cam is here Its all spanish to me but my motor builder thought it would work good. I had affordable fuel injection set me up with a custom chip and wiring harness. I had pulled all the other stuff on an 87 pick-up. There chip eliminated the egr, knock sensor, esc, and vss. Sure made it simple to put it all together. ANyway, my problems. First trip out i had no low end power. It would actually backfire through the tbi at full throttle and low rpms. (dont know actuall rpms, i dont run a tach). BUt it seemed to have decent high end power. I had the timing at 12 degrees inital timing. ANd the O2 sensor (3wire) about 8" down from the collector. Second time out. Moved the timing to 4 degrees. Lost a bunch of power. THird time out. Set timing to 16 inital. Moved O2 sensor into the collector. Ran a scanner on it. All seem to check out except the O2 sensor reading. Normally it would read about 400-880 mv. Sometimes it seem to stay at 004 mv. then pull a code 45 rich exhuast. Then pull a 44 lean....... Had way better power on the bottom end. But i could still get it to backfire through the tbi if the rpms were low enough. So, i guess my question is, how much inital timing can i give it??? just go till it pings? Also i have a wierd idle. It seems to "hunt" for an idle. Idle goes low, then back to normal. I was told vacum leak. I have checked twice now for leaks when it was cold with starting fluid. I cant find one... It does pull 16" of vacum at an idle. I have done everything but get a fuel pressure reading. Would that help?