My Mom gave me her 91 LeBaron convertible with very low miles (33K). The issue I have is that when the temperature gets hot outside (80+), the car won't shift from 3rd to 4th. When you start the car and drive, you are good. If you make a couple of stops, then the shifting issue happens. I had the alternator replaced in February and we have been driving without issues. I thought the problem was fixed with the change in alternator but once the heat hit, the problem is back. We have replace the shifting solenoid and that didn't fix this issue. I was thinking it was affliated to the cooling system since it only happens when the temperature is hot, but what do I know. The car did sit in the garage for 3ish years, without being run. Any clues from anyone?