Hi everyone I am new to this forum and new owner! Around July this year I bought a 2003 Monte with 199k miles, it was a one-owner and from a family friend. It ran fine, all it needed was a new O2 sensor. I bought it, got a new O2 sensor in it and everything was fine for about a month. It began to have problems starting, it would take 5-6 tries in the mornings only to get started, but after it started in the morning it would work fine the rest of the day. The car has new spark plugs all around, ACDelco iridium plugs, wires look fine. I removed all 3 coil packs and ICM and had them tested at the local parts store. They tested good. Check engine light was on and was throwing a P0128 code so I put in a new coolant temp sensor hoping to fix it. Still no dice, took it to a local mechanic and he diagnosed it to be a cam sensor and put a new one in. Said it was getting fuel at the injectors and spark. It worked good for maybe 3 weeks after the cam sensor was installed then took more effort everyday to start then finally wouldn't start at all. It would crank fine but wouldn't start. Tried harder than I should've to get it to start for a week and fried the starter. Took it to a different shop and was told that besides the starter, the ICM was most likely the problem. Once they rebuilt the starter though it ran fine. So I took the car back and had no problems for a few days until this weekend. The temperatures dropped again and the car wouldn't start. So I have come to the conclusion that the car will not start unless it is above 60 degrees F outside. As it is starting to get colder out I really need to figure out the problem as this is my daily driver. Today in the morning it was around 55, car would not start. Waited until the afternoon when it was warmer and it started right up no hesitation. I drove the car over 100 miles, stopped and started the engine 5-6 times, with at most an hour in between starts and had no problems AT ALL. Only code it is currently throwing is P0128 again, the car will only get to operating temperature if I let it set and idle for a few minutes. If i don't let it get warm and drive it it will not get past 1/4th on the temp gauge. I am at my wits end and I cannot figure out what the problem is, no amount of internet research has helped as I haven't found anyone else with this same problem. If there is any more information to include let me know and I will update this post.
Update: Finally found the problem, it was simply a cracked wire in the harness going to the crankshaft position sensor.