2005 Silverado 2500 V-8 gas/standard transmission. I'm trying to track down the cause of a low speed lurch that shows up randomly at about 2k RPM on a specific mildly bumpy road. The truck will act like the engine is bogging for a second on rough patches, but I'm not able to reliably reproduce it. I assume there's something loose or worn in the drive by wire throttle, but I've not been able to track it down in a year and a half.

New MAF sensor, new throttle position sensor, cleaned the throttle body and didn't find play in anything, new plugs, new plug wires, replaced two coil packs (others tested normal), replaced an injector (others tested normal), cleaned the injectors, cleaned the fuel rails. New clutch/master/slave & brake job. All the wiring on the engine side of things is tight: cleaned and dialectic grease on all connections. Only thing that made somewhat of a difference was when I replaced the tires. The shocks probably need replacement.

My two theories are either that the gas pedal position sensor is going out/has a loose connection, or that the crappy shocks bouncing me around actually shift my foot enough to drop throttle input but not enough to notice. Or possibly an early stage failure in the throttle body itself, except it's not throwing any codes and seems in pretty good shape.

Anyone run into something like this before? Switching jobs, need to change all four of the a/c blend door motors, and cash is tight right now, so I don't want to just throw parts at it if I can help it.