Chevrolet C1500 stalls upon startup and makes loud thud at 200 RPM on Chevrolet C1500

Some Chevrolet C1500 owners report experiencing stalling upon startup, which may be caused by issues ranging from a faulty fuel filter to more complex problems with the engine control module. Additionally, these owners have noted a loud thud noise at 200 RPM, potentially linked to a clunk during startup due to residual transmission fluid in the clutch packs. It is also reported that ambient air temperature has minimal impact on engine startup RPMs when the engine is cold, as high idle is normal after the vehicle has not been started for several hours. Furthermore, some owners have experienced a single knock upon startup, which could indicate a faulty wire or a failing fuel injection system, with persistent knocking suggesting the need for fuel injection system replacement. It is recommended that affected owners have their vehicles inspected by a qualified mechanic to diagnose and resolve these issues.