Powertrain Vibration?

[Devil_concours]

since my dealer is so crappy and i have had so much problems with it, i can't tell whether the mild vibration on the highway is coming from the drivetrain, steering wheel, or suspension/tires.
How can i figure this out?

[the Sandman]

[Devil_concours]

i did have a stability reduced message come up once last week and hasn't comeback on yet. I can kinda feel it when i'm stopped i'm kinda guessing that this could be a motor mount problem and yes dealer did touch the motor mount on my car. it has about 96k mi on it. I thought it was the wheels that needed to be balanced I guess i was dead wrong. It's hard to explain. It kinda seem as if my steering wheel rod is connected with a pin and it's getting loose that's what the vibration feels like. Vibration feels sharp at times.

[the Sandman]

[Devil_concours]

well it kinda feels like the vibration is near constant through 55mph+
There is less vibration when stopped but there is still a definite vibration.
It seems to vibrate little bit more when i release the accelerator
I can kinda hear noises when i let the accelerator go(it sounds like big tire noise but i didn't have them before) On very light acceleration/cruise, i can kinda hear the transmission as if it's overheated(sounds kinda like fullsize pickups at starting from stop light with ac balsting in hot summer).

I have no idea what's going on but dealer has worked on following items
1 motor mount replaced
transmission had major work done after it stopped shifting into overdrive just after they did the transmission fluid service
head gasket (prolly caused by the overheating problems i've had)
numerous spark plug and wire replacement(car started to misfire and it was prolly due to overheat and gasket)
wheels were balanced just few days ago and it feels exactly the same as it was before

[the Sandman]

[Devil_concours]

Originally posted by the Sandman
I'm no expert but it sounds to me like you have a serious problem in your engine and/or trans. Is the power level normal? How are the shifts? Is there any slippage? Are you still under warranty?? How much "overheating" are we talking about - enough to damage pistons or other engine internals? Head gasket went? I'm thinking engine damage...

well dealer has touched every item i listed in last 5months or so. They are all technically under warranty for now from this dealer. I'm even thinking of considering taking this to small claims since they can fix my car right and i gave them plenty of time to do so.