So this morning I was driving to work down I-65 doing about 75mph and I had this horrible shake/shudder/vibration only when my foot was on the gas, but as soon as I let off the gas it would subside. It does it the worst over 70mph but it starts to be noticable around 55mph.

Any clue what this could be???

Sounds like what jr'* 3800 I believe is looking for. The torque converter clutch solenoid is acting up. I had one go bad on a previous car & it done the same thing as you are describing. If you try like jr suggested by driving with the car in 3 instead of D & it stops that will most likely be your problem.
Also watch your tack wile it happens. You will see it jump back & forth a couple hundred RPM from the TCC engaging & disengaging.

I'll do the 3rd gear thing and see what happens. I ahd a funny feeling this morning that it was tranny related :?

This is something I so don't need right now

I'll get back to you guys after the next time I'm on the highway

I feel your pain, I've sunk a small fortune in my Bonnie over the past few weeks fixing all it'* little problems.

Honestly, I really haven't put any money into mine yet except for appereance things, but me and my fiance are closing on our 1st house tomorrow morning and obviously have no spare money with Christmas and such. Atleast she'* parked for the winter 99.9% of the time. I only drove her today because she had gas and my t-bird didn't.

Ok so I tested this while out on lunch, it'* now doing it a little in 2nd gear, but when I stay in 3rd gear it'* just as bad as when it'* in 4th gear.

No SES light, and no codes in the computer. I'm completely stumped

Like I stated above about it being just as bad in 3rd as in 4th, it still subsides when I let off the gas.