My pastor has a 1999 Olds Intrigue. When the weather is cold and the engine is cold (40 degF and lower), he has trouble starting the car, and keeping it running. He has to "baby" the gas to keep it going, and if he gives it too much, it sputters and acts like it's backfiring. Here's the crazy part though. Once the car warms up, it comes right out of it, and runs fine. He told me today, that when he takes his boys to school, it will come out of it in the EXACT SAME PLACE every time. It's like there is something in the ECM that changes when it reaches a certain temperature. ?
He's had the fault codes checked, and it has shown the upstream O2 sensor, which I have replaced. A Mass Air Flow sensor code, and a multiple/random cylinder misfire code.
He told me this only happens when it's colder outside, and when the engine is completely cold as well.