I pulled into my driveway and shut the car off. Something just didn't feel\nright as the engine shut down. It had been driving just fine up to that\npoint. When the engine was started about 30 minutes later, ran like crud.\nRPMs were all over the place and sounded awful. At high idle things smoothed\nout so I figured was not a critical problem. Engine was still hot and no MIL\nlight yet.\n\nDecided to drive to my buddy's to use his scan tool and try to figure what\nhappened. The trip is about 8 miles and on a straightaway, I opened up the\nthrottle (really stomped it). Ran at about 6000 rpm for a few seconds,\nremembered that there was a speed trap ahead and slowed down just in time\n(whew!). Came to a stop light and was expecting the engine to be bad again.\nDropped down to a smooth idle at 550 rpm and has been fine ever since. Never\nbothered to read out any codes but I will assume that something got lodged\nin the EGR valve and kept it from closing properly. There were no external\nvacuum leaks I could find.