Steering vibration/issues.

I am having some weird steering wheel vibrations happening. Here are the symptoms:
I have an intermittent shake when I go over 55mph. I have taken it all the way up to about 80mph and it still has a shake. The weird part is the shake starts off subtle, then gets more aggressive, then mellows out to the point where it isn't shaking anymore. The speed is kept consistent and this is happening. Any Ideas? It could be a wheel balance issue, though I have never had it start and stop with a balance issue usually is just consistent. I had an alignment when I put on the coilovers too. Also, along with the vibration, if the wheel is vibrating and i step on the brakes I get a very aggressive vibration in the wheel, but if the wheel isn't vibrating there is no shake when I brake. My lug nuts are also torqued down. I could just go get a wheel balance, but want to know if it could be like a tie rod or something else that might be going bad that needs replaced.

Thanks for the help.

Shake it down. if you can, get it up on a rack and see whats worn out. Could be just about anything.....

having your wheels balanced wouldn't hurt. its cheap enough that its no biggie if it doesn't fix the problem. i have seen several high-mileage cressidas wear out their driveshaft. i had one with bad U-joints and it made it vibrate.

get under the car and jiggle stuff until you find out whats toast...

Ive been having this same problem. Ill be getting an alignment tomorrow, but Ive literally checked everything else. Tore the front end apart and tightened everything back up. No play in either balljoint, nor tie rods, strut mounts, wheel bearings, lugnuts, control arm bushings, stabilizer arm bushings, everything is tight. The steering rack bushings werent exactly the tightest, so I tightened them and it did seam to help a little. But I didnt have this problem when they were horribly worn like when I first bought the car.

bent rims, choppy tires, wheels off weight....there is a lot of things.

My problem turned out to be strut related, the rubber at the top of the strut broke. After it broke, the car is riding WAY smoother. Ive got another set of struts Imma swap in and Im hoping that actually fixes my problem.

Probably the front bearings. Between my own cars and working at a shop I've replced dozens of sets. No two sounded/vibrated the same. I've had them almost shake off the road with barely a visible mark on the race and ride smooth as butter till 80+mph with half the race FUBAR. One of mine sounded like wind noise but only from 35-40 mph. Many times I've had them make a noise or vibration only at a certain speed or range of speeds. or be torque direction dependant (accelerating, decelerating, coasting). probably half have no play because "careful" mechanic wannabes just tighten the loose ones rather than actually checking or repacking.

OK just an FYI for EEEEEVERYONE that steering dampener on the rack. delete it.
it does nothing but cause problems, ie. vibration, wheel not centering after a turn etc. LOTS OF STUFF can all root to that little asshole.
As well go ahead and replace your rack bushings with ones from xcessive manufacturing. It's the best decision I ever made in terms of steering issue correction.