Car sometimes has problems starting when cold, starts fine when warm. on 1999 Chevrolet Prizm

I recently bought a 1999 Prizm with 153,000 miles on it. It ran a little rough when I bought it but didnt' burn oil so I put new plugs and wires in it as they were in bad condition. I ran a couple cans of Seafoam and a couple bottles of fuel injector through it as well. Car started and ran great after that until it got cold this winter. On cold days it would occasionally sputter and die while starting it cold but ran and started fine when it warmed up. I read that a simple fix was the coolant sensor, so I replaced that. It seemed to help and it started and ran fine on some very cold and snowy days but then started doing it again. I've worked on cars a lot and am retrofitting a TBI system on my old jeep engine, but I lack a lot of practical knowledge and troubleshooting ability with fuel injected engines. By the way, the air filter was brand new when I bought it, oil is clean, no leaks or burning oil, and the old plugs just looked like they'd never been changed. Any ideas?

by in Pacific Junction, IA on December 12, 2011
1 answer 1 comment
ANSWER by on December 12, 2011
Is the Check Engine light on? I suggest to hook up to a scanner and check values like air intake temperature while engine is cold.
COMMENT by on December 12, 2011
Sorry, I forgot to mention that. No check engine light, or I would have had it coded at the parts store. I do know the check engine light works though, because it was on when I bought it because the previous owner didn't have the gas cap on tight.