Thanks for the response. The car has 92,000 miles on it and it has never been emissions tested. The supercharger was replaced by the prior owner and the intake manifold gaskets were replaced at that time as was the water pump and even the A/C compressor. The car does not use any oil. The the ECM module has been replaced as well. My mechanic replaced the EGR valve free of charge this last time which was about four weeks ago. It was running just find until this weekend when I took it for a 2 hour round trip at speeds of 65 mph. It is now acting up again. The check engine light comes on all of the time now and when it is not on the car still runs rough. I have a crazy thought. The exhaust system is rather rusty and it has a leak near the front of the car. It is not too loud yet, but there is almost no exhaust to speak of at the tail pipe. I purchased the car from a fellow that stored it in barn. Could something be in the exhaust system such as a nest or something causing excessive exhaust pressure causing the valve to fail? Thanks, Brian