HELP!

I just bought a 1993 400sel, w140, and I'm trying to fix a few of the bugs that came with it.
When driving with the cruise contol on, the car will surge ahead for a few seconds and then return to normal. I noticed that the rougher the road the more times it will surge. The speed, it is set at, doesn't seem to make any difference on the the amount of times it will surge. I think there may be a problem with the amp. Can somebody tell me where it is located or should I be looking at something else.

Also when braking, there is a lot of vibration when stopping. Does anybody have an idea what might be causing this?

Thank you ,


Steve
stevekremer@yahoo.com