I have a 2000 3.8 naturally aspirated. Problem is that after it warms up it surges and dies when starting. Fuel pump, MAF sensor and IAC are new. Replacement MAF sensor is a new Delphi part from Amazon that was put in 4 months ago. IAC was replaced one week ago. When each of these items was replaced, it seemed to help the problem for a little while, but it really has not fixed the issue. No apparent vacuum leaks. Once its running, the MAF sensor appears to read in the correct range (around 5gms/sec) and is steady. It also appears to react correctly when revs are raised. Fuel pressure is at 40 psi and does not surge or drop on startup. If MAF sensor is unplugged on hot startup, the car will start and surge 2 or 3 times but it won't die like it does with the MAF plugged in. I've checked battery voltage which is okay. Air cleaner is not restricting air flow. I've removed the new MAF sensor and cleaned with with no change. Once the car starts and settles down, (by holding rpm at higher level with the throttle) it runs and drives fine. Is the MAF sensor not reacting quickly enough? Is the PCM not sending signals to the MAF quickly enough? No trouble codes are present. I'm most inclined to think that I have infant mortality on the MAF sensor.
Update as of July 2014 - I have to say I have been surprised that no one has run into this issue before and has an answer to the issue. Fortunately, we had a long cold winter in Wisconsin this year and the surging has not been an issue in the colder weather. This spring I had to replace the AC condenser so I took the opportunity to do a really good coolant system flush on the engine. Even then, I've noticed that now that its gotten warmer, there has been some evidence of the surging. I just replaced the after catalytic converter oxygen sensor since it was shot, and so far, there has not been evidence of surging.
