For some reason every time I take my Camaro up to 55 and over and release the gas pedal the service engine light turns on. Now I have tried to clean the EGR valve twice and the problem reoccurs, I now have a feeling that the transmission is having trouble shifting from third to second gear. I don't mind etting a new EGR valve but I would like to avoid any pointless expenses. Any help would be greatly appreciated.

The check engine lite tells you what you should do. Get the car scanned and see what the complaint is about and take it from there. Check for retained codes if the lite is off at the time.

It could be something as simple as a bad oxygen sensor in your exhaust because Camaros are notorious for having the oxygen sensors go bad in them.

Given it's an OBDII equipped vehicle, there are literally over 1,000 circumstances that the MIL will be illuminated. It's pretty much guesswork until it's scanned :-P