It appears you have tac/throttle actuator control. I'd check for trouble codes related to that system. To check codes, yourself, at the least you need an obd2 code reader that will work with your vehicle and read manufacturer specific codes as well as p0 codes. You might take an old tooth brush and clean throttle bore as well as throttle plate. Don't force the throttle plate. One of the modes for tac, will shut down tac motor--fuel injectors and ignition coil. The information is GM tac.
Sunday, March 3rd, 2019 AT 1:33 PM