I have a 1998 Jeep TJ. Two problems: When I hit 60mph, it shakes. When I get over 60 it stops. I have had all the work on the suspension done (including a new rear end..ouch!) and have 4 new tires but the problem continues. Any ideas on that one? Also, no matter how long I let it warm up, it spudders and studders going down the road. If I get going for about 5 or 6 miles it stops but the engine light comes on. Any ideas on this one? Sad to say but all the repairs I have done may cause me to sell my baby. Please tell me these are an easy fix!