Stalling when cold??

I was hoping some of you guys could throw some things at me that would make my car stall when it was cold. I got up to drive it at 7:30 yesterday and it ran like hell, stumbling and stalling all the way up to 30 mph. I didn't try to get it higher than that, just drove it home. Today I went to take it to the shop at around 2pm and it ran just fine. Good as ever. It is a 96 Century.

I'm guessing it's the oxygen sensor or something similar. Any help would be appreciated.

ps - it's got 140,000 miles. the catalytic converter and spark plugs are less than a year old. the fuel and transmission filters were changed last week with the oil and filter.
:banghead: :banghead: :banghead: :banghead: :banghead: :banghead: :banghead:

Basic tests need to be done, fuel pressure, coolant temp sensor inputs to the the pcm and a full scan when it happens.

Almost sounds like an engine coolant temp sensor, though I'm not saying to replace it. It may not be sending the correct voltage to the ECM and the ECM may think the engine is hot. Anyways, good luck.