[03hothemi]

Originally Posted by quicksilverdon

Damn. You've covered all the common causes.
Other thoughts:
Motor mounts - I've read of some failing.
There are counterbalance weights in the crankcase - driven by chain - could that have broken?
How bad was the overheating you had? Did you lose coolant? Did gauge go into red? I'm thinking minor head gasket leak...
Dunno...

Well...I'm not a novice at this stuff...but I ain't no pro neither...i guess that's why were all here. It seems that a collective of minds can solve just about anything...other than in politics and religion, right?

I've considered motor mounts being bad. The only problem I see with that is that the motor itself shakes, but it never shook this much at all. Failing motor mounts would tend to transfer what I believe to be much more of the roughness into the car than what is actually occurring. By the way, how much should the motor move when the car is put into gear?

I really hope that internally this motor is sound. I would suspect that if counterbalance weights were off that I would feel the vibration throughout the entire range of RPMs, not just at idle. Once the car comes off of idle, it is perfectly smooth. No hitch in it's get-a-long whatsoever.

The car never actually overheated in the since that it ever lost coolant. The gauge never went red. I have to say, my wife keeps a pretty sharp eye on her gauges. And, I have noticed no coolant loss in the past few months, other than what was lost and replaced during the fan replacement.

Funny thing...the sticker on the car says .040. When was the plug gap spec changed? Just out of curiosity more than anything. I just re-gapped the plugs. All of them were at .060 plus. It looked like the plugs have been in there for 100k but I know damn well I put a new set in last summer. Oh, and by the way, I lied earlier. I put champion plats in my truck, and autolite plats in the PT. I'm gonna go later this week and buy a new set of champs for the PT and see if that solves the issue. I did notice that after setting the gaps between .038 and .040 that the idle did somewhat smooth out, but is still rougher than my friends 06.

Any other ideas?