Hi, i drive a 90 240 dl automatic. Sometimes when the car has been driven for a while (@40 min), i will stop and when i put it on park or reverse the check engine light will come on and the car feels like its about to stall. If im going in reverse the car has stalled multiple times although it starts again with no problem. If its in park the check engine light goes away when i press on the gas. The problem seems worse if the car was left in the heat for a while. Any ideas on what the problem might be?

 

forgot to mention that about a month ago i checked the temp gauge because sometimes it wouldnt move once the car was warmed up , and it was working fine. the car ran well though and it had more rpm's at idle(750) than it does now(500) .Now the temp gauge shows normal temp just @ the middle but the car is running considerably worse. From reading posts about people with similar issues seems like it could be the O2 sensor , fuel filter or maybe even the timing belt ( never changed , car over 200,000 miles, od stuck @155). i would greatly appreciate any input or ideas on how to narrow down what i need to do to fix this. Seems to be getting worse, chk engine light coming on when car is warmed up and idle, @ stoplights i have to give it gas to keep it running...