what is wrong with my front and rear suspension?

The rear hopping and then sliding out a bit in a turn when hitting bumps at higher speeds is normal for stock suspension and it's something you will have to learn to control. There is also a good chance you shocks need replaced.

As for the front I have no idea without checking it out myself.

The rear of my car does the same thing and my rear suspension is not stock, but i got used to it, the front on mine likes following cracks and almost pulls the wheel out off my hands when the road is uneven, i replaced my inner tie rods cuz i had alot of play, but it still does the same thing so i dont know what causes that, my next step is replacing the rack.

Given that all of your bushings and ends are tight then replace the shocks/struts. What is happening is your shocks are unable to control wheel bounce when you hit an irregularity (pot hole) in the road surface at speed. You may have to try different shocks to find the ones that suit your combination of tires, tire pressures, vehicle weight, the way the weight is distributed, driving style, power, chassis settings (front end alignment) etc...

You can also get adjustable shocks/struts and avoid the whole "experimenting with different shocks" game.

You do not have to learn to live with the problem and it is relatively easy to fix.

i had the same problem with my front suspension, felt my hole steering wheel move( wiggle) whenever i hit a bump. About a year ago i was turning left through an intersection and my steering linkage came disconnected. Luckily i jammed on the brakes and no one hit me. I had about 10 people immedielty jump out of there cars to see what the problem was ( becuz i was stopped in the middle of a 4 way). they all pushed me into a parking lot as we pushed on the tires to turn the damn thing, luckily i had a toobox in back and it was a 10 min fix. ..scary as hell tho

I'll say this much, I have the complete MM Road and Track kit along with a T/A. My car still side steps when I hit big bumps going around turns at high speeds. It's not scary, it just lifts up a bit, the entire car slide out about 1 foot and then it just keeps going like nothing happened. No matter what suspension you have and no matter how good you are at driving you can't change physics. If you are going around a turn and remove enough weight off of the tires the car is going to slide out until there is enough weight back on them to get traction again. If this doesn't happen to you, either you aren't hitting big bumps or you aren't driving fast enough. The only thing suspension is going to do is make it easier to control and a little less likely to happen, but it will still happen if you are pushing the car. If you drive like granny I suggest skipping the suspension and selling your mustang.

Note- This is not targeting anyone, just making a general statement on the thread. Hope it helps.

*EDIT* And if you guys ever watch SCCA racing, you will see the same thing happening to full on race cars.