I have an 02' PT cruiser New problem/ after driving about 200 miles, any road irregularity or bump will cause the front end to shimmy dramatically. this is at speeds of 60-70 mph. If i let off the accelerator it stops immediately. If i accelerate it gets worse unless I accelerate quickly, then it finally goes away. Then as I am coming to a complete stop from about 5 mph the steering wheel shakes violently. I have replaced calibers and rotors and the tires have been checked for separation. Again this only happens after highway driving of about 3 hours. If the car cools down for 5-10 minutes the problem can not be duplicated. Has anyone else experienced this?