no power

Hi, I'm new on here, bought a 94 suburban in February. It has never had a whole lot of power and only gets like 9-10 mpg. Lately, though, it has started to stall right at start up when the engine is warm (20-30mins after stopping when running to the store or something). My wife thought it might...

I have a 1995 4x4 jimmy, a week ago I got a amp and subwoofer to put in it. I took the radio out to hook up the remote wire and I did not touch any other wire but after that I have the check engine and abs light on. The power windows, radio, and temp gauge do not work now, anyone know what could...