RPM Drop and dieing 94 LHS

I have a 1994 Chrysler LHS 3.5 V6 engine and when I go to stop at a stop light or sign the RPMs drop to 500 and sounds like the engine is going to die. What would be causing this? Any help is thankfully taken. PLEASE HELP ME WITH THIS.

Okay now I have a new part of this problem. I took the car for a long drive and when the engine was at operating temp. and I stopped the engine died. What would cause all of this ... low RPM at stop before operating temp. and then dieing at stop when operating temp. has been reached.

Had same prob. Your catalytic converter is plugged up!!!! All that exhaust is being back-fed to the engine and stalling it out. Have it replaced and your on your way.

Good luck!