[Walt Fricke]

OK

If you are comfortable setting valve timing, you can do it with the engine in the car. Jack the car way up at the rear. Pull the muffler and the rearmost engine tin and the tensioner oiler line. When you take the chain cover off you should get very little oil spilling out (reason to jack up high). Then set the left overlap closer to the right, since both are within spec. I find it hard to imagine this would cause the engine to feel like a cylinder isn't pulling its weight, but since it bugs you - - -. One more thing down.

Do you have an IR heat gun? You can use this on the exhaust manifolds close to the head to see if a cylinder is cooler (or hotter) than the others. Might help if you could put the car on a lift to do this, as all are not equally easy to aim at (nice to have that red dot on the thermometer device).

I suppose you could put it on a chassis dyno, and compare printouts with other 3.2 owners.

Is the lumpy sound only at idle? I understand that the idle air controller can be serviced. The usual complaint is that the idle speed is off, so that's a long shot.

Out of ideas.

Walt