My car runs rich at startup for about 45 seconds. It usually starts with a puff of black smoke. If i try to drive it during this time it stumbles and hesitates. It has also had a problem with a very slight momentary hesitation occationally at speed. I've checked and replaced several likely sources: fuel pressure regulator is good, replaced suspect engine harness, checked and cleaned iac, new heater valve. My mechanic said the injectors aren't leaking. Just cleaned throttle body and reset idle. After grounding the red/white wire by the battery, i set the idle to 700 rpm. When disconnecting the red/white test wire (to re-engage iac) the rpm reved back up to around 1400 and that is where it seems to stay as i drive around. Does this mean the IAC is suspect?

While searching the brickboard I found a 2001 question from ringlee about the cold start injector. He was having trouble with rich running for the first 30-40 seconds and suspected the cold start injector. Does an 87 740 have a cold start injector? If not what is it that did the job of a cold start injector in that model. If so what might i do to get it to function properly?