About a month ago my check engine light came on while driving. I stopped several times before I got home and somewhere along the way it reset. About two weeks ago I got another CEL first thing in the morning on my way to work, again it reset after sitting. This week it popped again and stayed on. I got a P0404 and reset it with the reader. That lasted a couple day and it's back on again. I can't find anything specific to GM, only a generic code, Exhaust Gas Recirculation Circuit Range/Performance. Bad EGR? Truck is an 03, all stock, and is running fine.