glad to see the OP figured out his issue.
fwiw my vibration was related to a failing steering rack. New steering rack installed and the vibration I was complaining about has been remedied.

Kabel, what did that new steering rack cost you?

rack by itself was 800

Yikes! That's a lot of money.

yes it is. I was not really happy about it.

FYI, my situation continues to mirror the OP's. My front tires had plenty of tread so i didnt think they were the problem, but psgr side was leaking so i took it in for repair. Shop found they were dry rotted and psgr side had a knot on the inside that was unrepairable. Said both had flat spots too. These tires had sat up for a long time because a previous owner didn't drive it much. Rears were rplcd recently and are in good shape.

So I got the Nexens on the front, $240 mounted and road force balanced. Only problem is shop said the psgr front wheel had a ding in it; not bad but probably bad enough to feel it.

Based on first test drive, the high speed shudder is gone. I believe now it was mostly due to the bad tire. But can still feel some unwanted vibration... I still probably need a 18" front wheel and maybe a motor mount. I'm at 80K miles.

But the good news is I can relax about a front end rebuild, at least for awhile.

Problem solved
 

Hello to all,
I started this tread some time ago. I received a lot of help and ideas. I wanted everyone to know that I finally resolved the problem this weekend. After all the issues with my tires, I still had a very bad high speed vibration in the steering wheel. I was ready to order some new rims and spend $500 to $700 on new rims for the front tires. As a last ditch effort I went to a tire store with a road force balancer. I told them I purchased the tires from another store of the same franchise and they can't get them to run smooth. They took the car right in dismounted the tires then remounted and roadforce balanced them. I was then told that they ran out great but the drivers side rear tire is not right. They can't get it balanced right because it has a high spot in it. they then ordered a new tire at no charge. They put it on today and WOW. I now have a very smooth running Box. I am a very happy camper again. I can't believe I have battled this since August. I am posting this back on here because there has to be a lessen here.

P.S. The tire store that solved my problem got 3 large pizzas delivered to them today for lunch. Cheap price to pay for great service and a fix.

Thanks again for everyone who helped.

As stated earlier, tires can be the culprit. I know it blew my mind when it happened to me several days and sets and balances. Nothing until they traded out the tires, then you like wow.

Good to hear you figured it out, my guessing the other store did not want to switch you tires.

It's not uncommon to see a brand new high performance low profile tire out of spec. I experienced this on two separate occasions with a pair of Goodyear Eagle F1's . Simple dynamic balancing will not detect this problem.

So it sounds like its not just about selecting the right tire but a reputable place that has the Road Force equipment to balance properly? Is this correct? I am in the market in the near future for some new shoes and wanted to check a few places out that can help properly. I have a little shimmy at 70mph as well as some of the other posters. Thanks in advance for the advice/help.