Looks like I'm getting my Ordonez on...so please forgive me for my ranting in advance but the T-Bat is starting to p*ss me off.
I have swapped out the springs per my previous post. I also swapped the right front hub that was worn as well as re-installing the stock length dogbones to put angle back right.
Today I put the car in the shop and had 4wheel align/rotation/balance done. the align was off quite a bit and the car does roll much smoother than before.
Yet this infuriating power-on vibration at highway speed still persists!
I am 99% sure this is not an engine issue since full and 3/4 throttle blasts for both a stop and low speed roll are strong and seamless. I can powerbrake the car all the way up to 3k rpm without so much as a quiver so I think an ignition miss is out of the question.
Given the time and money spent already I'm getting very tired of playing hit & miss trying to solve this issue. I am also constantly nagged in the back of my head at how maint this car has had at only 126k miles vs other cars I have owned...if I didnt like the car so much I would have already unloaded it

If anyone has substantial ideas on what could be causing this problem I'm all ears since I am not interested in continuing to drain my bank account.
Axles?...mounts?...I just dont know at this point which I'm sure is partially fueled by my frustration level.
If my car doesnt do anything else well I do demand good highway performance...I am in no way entertained by the concept of a long drive of constant vibration and shaking every time the throttle rolls on in the slightest.

I really hated being this pissed at my car...is this how Batman gets new a ride? (aside from a villan blowing it up)

getting your ordonez on... I like the sound of that.

how about the lower motor mount? has it ever been replaced?

I'd also place bets on a worn cv axle.

Possible on the CV's, but you'd really hear feel it on turns.

Have you tried putting the shortened dog bones back in to see what it did? Motor mounts are possible.

Hmmmmm.... Call me sometime and we can discuss this further. Trying to think of all the possibilities.

anyone got pics or how-to on motor mounts?...or how to check them out?

I'm with Slick on the CV joints...I've turned tons of circles in parking lots, right, left, slow and fast and it makes not a peep. No popping or crunching of any kind...then again I suppose if the joint closest to the tranny is goin south it might not have those symptoms.

If a mount was bad wouldnt I get a "thump" or something when I change gears? forward to reverse or such?...when I powerbrake it doesnt thump or rock then either.

Not neccasarily. The stock rubber will harden. It'll lose it's ability to dampen vibration before it goes full tilt bang bang when loading and unloading the motor.

My wifes bike has been giving me fits and was getting frustrated with it. Even thought of swapping out the drive train from mine to put into hers and trade out mine lol. But after a few hours in the garage I finally got everything fixed on it. Best part was it didn't cost me a dime. Turned out between the intake manifold half on half off and mis routed throttle cables was causing all my issues.

at Slick's suggestion I swapped out to set of shortened dogbones I had made before I bought a set from the W-body store. I'm assuming if compressing the worn mounts (since they have run that way since I went to TMS) helped the problem maybe it would narrow things down.
I changed them as soon as I got home from work tonite and took a quick test spin. The vibration does seem to be less but I'm also feeling more of it when I turn than I did before. I suppose this could be from bad axle angle since the engine is rocked forward on the stock spring setup...then again Rook could be right about the CV going bad.
Bottom line for all this right now is that I only have two days before we are set to leave for Connecticut. I wanted badly to get the car straight so I can hook up with BlackArrow for our mini-meet, but I'm not gonna spend the next two days flogging and spending more money on "maybe this or that"...looks like the T-Bat gets parked and I'll be taking the Sebring. Maybe after I come back I can get after this problem with a clear head.

At the end of it all and after thinking about it, I would probably encourage you to change the motor mounts no matter what the final cause be.

Reasoning is that you have a car that's getting up there in mileage and it'll need them before all is said and done with.

I'll see what I can do about a write up, but I'll have to borrow a gp from someone for the pics unless I can find some in my collection already that'll work.

anybody got "how-to" on swapping axles?

just call your online tech support...

he's available 24/7 as long as you can wake him up when he's sleeping...

You can use this Wheel Bearing Hub Replacement as a guide, but instead of removing the hub, you'll need to separate the outer tie rod, sway bar end link, ABS connector, and lower ball joint from the spindle, then once you clear the spindle from the axle shaft splines, use a prybar or big screwdriver & hammer to pop the inboard cv joint shaft out of the transaxle, which is held in with a snap ring.
When you install the new axle, make sure the open ends of the snap ring are facing downward, (it'll pop back in easier) then support the axle shaft and tap it in with a hammer; you should hear it "click" when it goes back in.

That's going way overboard on things to tear off...

I only have to undo the tie rod end, axle nut, and maybe the strut to knuckle bolts. Makes like a bit simpler. The pry bar bit works sometime, but only on the driver's side. On the passenger side it doesn't work so well.

Slick,
I was going to suggest your method as an alternative; I usually try to do as little as possible(leaving the calipers & rotors on, etc.), but it depends on the car..as I said, use it as a guide.

well I picked up a set of mounts today from Autozone and I will try those in the morning (I know, I'm a hopeless case) i cant leave the car alone knowing it isnt working right. I also know what great hiway cruiser it is when its working right.
If the mounts do do the trick then I have a last shot friday morning to have axles swapped out...but I may put in the shop for that. I asked today and he said $189 to get it done. I would consider doing it myself but I have to get some sleep friday before I hit the road that night. I'll post up before I go for last results.
A big "thank you" for tech support and all your responses. I may be shouting tomorrow on motor mounts