Mits. Lancer crank sensor/ timing belt

Greetings, I was hoping to present a question to the board and get some opinions. I drive a 2003 Lancer with 80,000 miles and recently had my timing belts changed. After picking up my car, and driving it back to work, I put my car in park, and it turned off by itself. It started up again no problem. I put my car back into drive, and put it back into park and it turned off again. It starts up easily. This did not happen for another 3 days, while I was waiting at a bridge opening, I put my car in park and it turned off again. When it does this, it goes down to 500 RPM, revs up to 1000RPM, then slowly drops until it turns off. When I brought it back to the mechanic, I was told it might be the crank sensor; however, it seems odd that a sensor would go bad the same day I have my timing belt changed. So I was wondering if anyone had any other opinion.

Thanks in advance,


I very much doubt that the crank sensor is the trouble. If the CEL light is off things should be ok with the sensors I would say. The first thing I would look for on this trouble is a disconnected vacuum line.