Outceltj, with all due respect he's right.

 

Thanks for the feedback bro, I will look into it. BTW sry for the mixup, my Mustang has 18' not 20'

 

I got wheel size mixed up with my other car. I got factory fitted 18' wheels that came as a part of Premium package from factory. I thank you all for your feedback and really appreciate your replies, So what should be the next thing I should check now? I don't have any play in the wheels while rocking them side by side or up and down, so I assume the wheel bearings are OK. also the tie rods feels tight. I am getting out of options here. I went to 3-4 different mechanic shops recently and all of them had different opinion. One said let's change lower control arms, second one said may be one of your rites has a broken side wall on the inside, third one said may be ur new Rotors are already warped out of the Box... What????????? At this point I am ready to spend money to fix the problem, but not to just replace everything in trial and error method than most mechanics over here suggests.
I will get the car up on the jack stands when ever I find some free time and try to go over and check everything one by one again. In the meanwhile, I am not taking it to freeway and just driving on city roads under 50 mph.

The funnies thing is that it's so smooth while driving, even on very high speeds 100+ , and the only time i feel that horrible steering wheel shake is while braking. Braking at lower speeds is so smooth that sometimes u just forget that u have a problem until u get up to say 55 mph and have to brake. That moment is very annoying and kills the drive for me...

I would love more feedback from yaall, if you have any other logical reasons please through at me. Thanks... In the meanwhile, I wanted to share a PIC of my Pony with yaall.....

 

Well I was with the guy. Rode in the car with surprising wheel shake. He did all the normal stuff such as the thread starter with no improvement. I asked if he installed sway bar and end links as I knew he had ordered them. He did. We swapped them out and it fixed the steering shake. I get that end links are not apart of the steering mechanism. I can't explain why it fixed the issue other than his end links were basically thrown on and loose. They were completely adjustable in the fact each one was so far off it didn't even make sense. It would seem adjustable end links that were far from properly installed were the culprit as we literally got in the car after the work was done and the shake was gone.