I have a '92 Chevy S10 Blazer. I checked the oil (needs to be changed but otherwise fine), transmission fluid and coolant, all are normal. Battery was replaced about a year ago as well as the starter (although the starter was used). I started it this morning, it turned over just fine but was idling high, seemed the engine was working harder than it should have. I let it warm up for about 15 minutes, heater was working as well. I've been driving it just fine for the past week. Yesterday was the first day I didn't start it. It's pretty cold today (I live in southern NH) so I added dry gas to the almost full gas tank thinking the line might be frozen and still nothing. It will turn over but not start. Possibly the alternator? I need some advice to decide what I should do now.

Replacing the Ignition Control Module (ICM) usually solves the problem.