I have to go with the coolant temp sensor. Had a 88 Celebrity (high mileage). When it was 15 - 25 degrees and relatively high humidity and having sat out all night the car would have to be cranked for over a minute -- many false starts and backfires -- once started it ran fine. I just carried a wrench and an extra sensor as I was on the road 5 - 6 days a week and being late for an appointment was wasn't an option. Less than 5 minutes work and I was on the road again.