i have a 81 rx7 and it does not want to stay firm on the road.
it pulls to either side and more loose when i hit any bumps on the road.
i had the ball joint checked and front end too -------- looks ok

 

What do you mean, It looks ok?
Could be idler arm bushings are shot.

Could be bad tire.
There is a specific way that play is checked on ball joints and tie rods.

How long have you had the car and how long has this issue been there?

 

If the ball joints "really" are fine, the idler arms et al look good - check for dried grease on the upper strut bearing. Some 90W gear oil over night may be used to seep in and loosen them up. I had to replace mine. My symptom was stickiness when backing up and turning or any sharp turn (would get a shutter). This also directly impacted the cars ability to caster properly

 

Could be worn front end parts, could be an alignement issue.

 

tires are good and recently did aliment
how do i check the idler arm

 

search under the late Blake Qualey and idler arm. nice illustration on how it works

 

Since no one answered your post, I thought i would try to help.
I had an 83 that had the same type of problem and was wrecked when I bought it. I found the cap on the worm gear box had worked loose. There is an adjustment screw that is supposed to be able to move, but that is mounted thru the cap. Make sure that cap is on tight or the worm moves up and down as you hit any strange bumps in the road.
Another item is the idler arm bushing mounted on the passenger side frame. These guys wear out and allow a lot of movement of the steering components. You can buy these real cheap, make sure it is new anyway. You can get them at your local dealer or order them from Black Dragon.
Hope this helps?