if i go above 50-60mph the car begins to rock left and right and gets tough to keep straight...

what could it be? I have new rims/tires to go on soon but wondering what else the problem could be..

 

Everything balanced properly? When you put the lugs on did you hand tighten them evenly then get them tightly secured one across from another so it was evenly secured?

 

did you get the tires ballenced? if not make sure to do that it shoudl fix it.

 

I haven't mounted my new rubber and rims yet...i'm still using my OLD bad tires right now...so im guessing thats the problem? i'll get a shop to put the tires and balance them...

 

Could be if your tires are bald. Also allignment.

 

considering your cars almost as old as me.. it could very easily be a loose nut somewhere.. does your car have any accidents ? my friends ford has the same problem due to a slightly bend a arm mount thats part of the chassis.

 

i had a crap load of vibrations (literaly too many) over 35mph. When i did the 5spd swap, I noticed a missing driveshaft bolt.

Replaced, and along with them, new halfshaft bolts.

First drive: not one vibration. After a year of getting used to vibrations, I didn't know what to think!!

 

Probably a bent frame. Have you hit any curbs lately?

 

worn control arm bushings? bad shocks? check those.

 

Check tire pressures. One shop had mine 10 PSI different frmo side to side and my car would become unstable

 

I expect is a combination of suspension & tire issues.
Any or all the following:
Front toe out.
Front castor angle too low.
Front A arm bushings.
Rear trailing arm bushings.
Rear DTSS bushings.
Rear toe out or in.
Tire belt cord problem.