I have a great plow truck 05 sierra that i switched out my ECM...Truck wouldn't start and figured out it was the ECM....Its running kinda rough so i figure its the ECM...I heard you need to have the truck at the dealer to have a flash done but then i see you can buy the ECM's on ebay and you just give them your vin number. Anybody ever have their ecm flashed outside the dealer? Any info would be great