Presently at work, waiting for tow truck. Started the Yukon remotely and when I got close it started knocking. All kinds of lights and then the CEL, idling super-rough. Suspecting lifter failure (21K on the odo). Anyone using the range Tech. AFM/DFM delete? I had one in my 2018 Tahoe but when I got this truck, I called Range Tech. and they hadn't developed one yet. I see now they have one for sale, anyone using it?