We own an Envoy XL 4.2L inline 6. Lately the engine surges when the vehicle is at a low rpm. It normally does this when going through a parking lot or parking into a garage or parking space. It only happens at a low speeds and stalls sometimes. Could this be a dirty fuel filter?
I would inspect the throttle and clean the throttle body if needed. There may also be an updated calibration available for your Envoy’s powertrain control module. The crankshaft position sensor (CKP) signal can be checked with a scan tool to verify proper operation as well.
If the fuel filter is due for replacement based on mileage (you can check maintenance schedule in owner’s manual), then definitely perform that maintenance. But a restricted fuel filter is more likely to cause fuel starvation under high RPM/high loads rather than at idle. If you need to have this checked, a certified technician from YourMechanic can come to your car’s location to diagnose the stalling issue and help you move forward with repair.