Might be a long post, as I will need to be descriptive and in depth.
I have a 1995 Pontiac Grand Am SE, four speed auto, 2.3 "Quad Four" engine.
The problem in a nutshell is that the engine will sputter and surge after a cold start up. It occurs anywhere from 30 seconds after to 1 minute. The episode will last 5 to 15 seconds. If I never engage it in gear for the first minute or so, it almost always does it, if I drive right away, sometimes it will, but not always. Here is a list of some things I've replaced through various problems and preventive maintance. (Some actually didn't need it but oh well....) Ignition housing, coils, spark boots, and spark plugs. oil/air seperator box, and hoses attached. Fuel pressure regulator vacuum hose, map sensor and vacuum hose, IAT sensor, TPS sensor. Timing chain and hardware, waterpump, flex plate, oh, oxygen sensor too. The engine is modified slightly. CAI, Cat back exhaust, and smaller diameter pully. Many that I've talked to like to blame it on those mods, but they have been in place for a loooong time, and although it's had this problem for quite a while, those mods were in place for quite a while before this issue. Oh, no codes ever show up also. The engine has just over 126,000 miles.
Now on a side note, many of those parts were replaced just as preventive maintance, as I have discovered with a few that the ECM won't always pick up on something being out of whack a bit, unless it's almost not functioning. From my experience anyway. Some of it can probably be blamed on me, because I haven't always been kind to it. But oil changes etc are done strictly on time. All in all I have to say I am very pleased with it. 9 years, and 126,000 miles, it hasn't given me too much trouble. And with an engine with one of the worst reputations ever! I've broken a few things on it, but live and learn I guess.....
Hopefully you can help with this, it drives and runs beautifully otherwise.
Tony