OK, maybe someone can help. I have a '92 RS 305 TBI that runs really well most of the time. The problem arises when I crank it up at the end of the work day - only in really hot weather. If the car has been sitting in 90+ degree MS heat all day while I am working, it misses, stumbles on acceleration and generally runs like crap all the way home. After shutdown it will resume normal smoothness after it has been cooling in the garage for 20-30 mins. This situation never happens in winter, fall or spring, only in the hot deep south summer. Unfortunate because the car is a convertible and I need it to run nice in hot weather. Does anyone know what sensor or (?) may be causing this?

 

Is it completely stock? Almost makes me think it might be an ignition module. They tend to get unhappy about hot weather. If it starts getting worse that might be something you'll want to look at. How long has it done this?

 

It is absolutely 100% stock, very well taken care of, low mileage, I am the second owner. I replaced the fuel pump 2 years ago and the alternator/belt last year; everything else is original. It has been doing this for about a year but remember, only when it gets really hot. I sort of forget the issue during the other parts of the year. Nowadays, when I crank it after sitting in the sun all day, it immediately runs up to 1500+ rpm, stays there and runs rough all the way home. 15 minutes after shutting it down in the garage I can crank it and it runs just fine. Any suggestions would be greatly appreciated...