When it gets over 80-85 degrees, my 96 neon runs like crap. I was driving on I-10, going about 60 when I felt the first miss. Then more often. As I pulled off on my exit, it stalled. I was able to stop on the shoulder and it would crank, but not fire. Since I was sitting there, I ran the codes: 11, 12, 43, 55. After about 3 minutes of sitting, it started up and drove fine. If I clear the codes, the car will run fine, till it gets hot outside again. Is it the coil pack dying because of heat? Or is there a fuel problem...like vapor lock or something??

 

If you run the engine codes with a code reader it will break the codes down into more precise codes.

Code 12 is a common code that just means the computer has been disconnected from the battery or the voltage momentarily dropped. Not usually anything to worry about.

Code 55 means completion of code display. Just an end of code data message and will always be present.

Code 11 can be one of several codes and a code reader will break this down.
Camshaft sensor, crankshaft sensor error or timing belt out of time by one or more teeth.

Code 43 is a multiple cylinder misfire. This is generally caused by bad spark plugs and or wires but, may also be a bad coil pack. In your case it may also be related to the code 11 as a bad or weak crankshaft sensor could possibly cause the misfire.

 

Go to Autozone and have them scan it and get the "P" codes. I'd do it for you if you were closer to me.

 

Update!! The codes cleared by themselves this morning, but the sensor affecting the coil pack makes a lot of sense. I'll go by auto zone and see what they can read. I'll let you know.