1995 626 chocking itself out

I have a 95 626 and I am experincing something that I have never encountered before. After the car is running for about 20 minutes my car will choke itself out when I release the gas pedal at a stop sign or stop light. So I have been having to keep both feet on the pedals to keep the car at an higher idle rate (2000 rpm) to avoid it form dying. This has been only going on for a couple of days but now my O/D light is blinking on. Please Help.