Engine surges

I own a 2003 Hummer H2 with a 6.0 liter vortec engine with only 62,000 miles. At 50 to 55 mph 1500 to 2000 rpm the engine surges 300 to 400rpm with foot steady on the throttle. There is no engine light on and I,ve checked for codes with a code reader from the auto parts store. No error codes. I’ve cleaned the mass flow air sensor and throttle body with no change. My next thought was to replace the throttle actuator control sensor or accelerator pedal position sensor. I do enjoy working on my own vehicles so have been reluctant to take it into the shop.

Before just continuing to guess I’d get it onto a scantool to collect real time data while you’re driving it. If you do enjoy doing your own work there are basic scantools that will do this starting anywhere from about $100 and up. You’ll spend a lot more than that on guessing about parts.