93 toyo pickup shakes on highway

Lowered how and how much? 2WD or 4WD? Are you saying the tires are balanced or should be balanced (as in "they are not balanced now and should be taken to a tire shop for balancing")?

I don't know if it's normal, but my '93 does it too. It doesn't shake as much when the windows are open.

Did you correct the caster angles after it was lowered? Perhaps the caster angle is in the negative now or even a simple alignment is necessary. I know in lifted trucks improper caster angle can lead to what is called "death wobble" and I suspect the same is true for lowered ones.

what is a caster angle and how can I fix it. Is it simple to alignment and cheap. If I don't have it aligned will it hurt the truck.

Lots of information on-line:

Duh, that's true. I have a solid axle 4Runner and tend to think of everything in terms of being a solid axle ;>) Camber is probably the problem. I know I see a bunch of those pothole scrapers around town here and almost all of them have the camber messed up with massive negative camber from doing halfassed jobs of lowering them.

don't know what a camber is. it was lowered by the mechanic I bought it from. lowered 2" with drop spitals and blocks in back

Take it back to the mechanic who did the job and have him finish it properly. I assume its a 2WD, since blocks will only lower a spring under axle setup. If so, was anything done to the driveshaft angles? Depending on the type of driveshaft you have, you need to address the angle changes either due to the blocks or if thay are tapered blocks, the angle of the taper and the lift/drop. Not too hard to measure the angles and determine if that is the cause of the problem:

If it's lowered, as in really slammed, make sure the diveshaft has not hit something and bent. First thing to check would be the tire/wheel balance. Second thing would be the driveshaft balance. Third thing would be maybe the axle is bent (ever been in a side impact?)

--- Rich