C4 is doing a mild idle surge similar to problem I had 4 years ago. Sprayed plenty of propane at all the hoses and gaskets --even tried Dad's golf club shaft. No obvious leaks.
Last time, fixed it by swapping out the TPS. Plan on doing plugs, an injector clean and then test & probably replace the TPS again this time.
Eckler's has an adjustable TPS with a vernier screw arrangement. Anyone tried this gizmo?? Like it ??
TIA