I can tell summer is here in Houston...my 96 Neon unexplicably dies when the weather gets hot. Cruising on the Beltway yesterday afternoon, suddenly the engine starts missing...I pull over to the shoulder and it stalls. I wait about 4 minutes, starts right back up...stalls again after about four miles. I pull over...wait about 3-4 minutes..it starts back up, and I get home with no more problems. I got two codes: P0351, and P1391...BUT WHY ONLY WHEN THE TEMPERATURE IS ABOVE 90??? From May- August, it does this whenever I do freeway speeds, and the temperature is high. The rest of the year, no problems at all. It's driving me crazy. What influence does the coolant temperature sensor have on the PCM? If it's whacked out, will it cause these types of problems??

 

I would think the P1391 would be the problem. As far as why only in the summer...can't figure that one out.