[AZKen]

It's probably an exhaust leak....manifold or pipe. I assume you have checked the oil and plugs for color. Assume no backfire at carb or exhaust. Starts and runs good, no major missing/stuttering. No smoke.

Also there is nothing special about our V6 motors as far as finding someone who "knows" them. It's a standard internal combustion carb and points motor. It has tune up, timimg and valve adjustment specs on this forum. Nothing different to troubleshoot than a Chevy V8. Etc.