This old man needs some suggestions.My 97 C1500 with a relatively new crate engine and fresh ignition components has a strange problem.With the engine fully warmed up the engine will, on occasion, start to severely bog down, misfire and not rev above about 3500 rpm. If you back off the throttle it will return to a fairly normal state. No codes are set during these episodes and if I stop and shut the engine off and restart it everything returns to normal and the engine runs perfect throughout the full rpm range.I have cleaned and applied dielectric to all the PCM connectors and pins and the tps, maf, map, crankshaft sensor , and the knock sensor pins and connectors..It almost seems like it randomly goes into 'limp mode"and when I cycle the engine off and back on everything resets and runs perfect. I guess I could have a knock sensor with an intermittant defect that causes the PCM to retard the timing or some other major sensor doing the same thing. I guess the PCM could have the same type of intermittant problem. The problem occurs about 2 to 3 times a month with no apparent common weather conditions.This is really hard to troubleshoot when there are no codes set. I have not seen this type problem discussed on this or any other forum. I appreciate any and all suggestions.
Al
Al