2005 Chevrolet Tahoe Electrical problems?

I have a 2005 Chevy Tahoe 5.3L that it giving me a headache. When your shut the headlights off manually three of four times in a row, the truck reads a "reduced engine power" warning, the traction control shuts off and you can't go over 5 miles an hour. If you shut the key off for a few seconds, then it will reseat itself and seem to run fine. A code checker will read an error "throttle actuator controll." Why would this be related to a headlight switch, and if so which parts of the TAC? By the pedal, by the throttle body? Not sure if any of it make sense but we have tried this "headlight switch theory" about 4 times and it has brought it I to reduced engine power everytime and the same TAC code is the only code that comes up.