I have a 1997 chevy cavalier, 69000 miles. It runs great BUT, when it gets below 35degrees, it will turn over and over but not stay running. After many attempts, maybe for an hour, it will stay running. Regular maintenance, and cold weather maintenance have been applied. New battery and cables. I took it to the shop and they could not find anything wrong. Got any ideas?
You need a new shop.
This is a classic sign of a bad temp sensor, and it won’t post a code because until the engine gets running on its own the ECU doesn’t post codes. If it did, every car out there would be loaded with false positives. If the temp sensor is bad, the ECU will not know the engine is cold and won’t ignore the oxygen sensor and let the engine run rich enough to keep going when it’s cold.
There are also other possibilities, such as a fuel line draining back, but you need a shop that does more than just check for codes.
It would be interesting to know what kind of shop.