I own a 1988 300E with approx 105k miles.

My problem/question:
While driving down the highway the car will slip out of gear and effectively be in neutral (when I press the gas, it just revs the engine). The car will then lose all power and turn off. Sometimes if I put the car in neutral, then back into drive before it loses all power, it will re-engage into gear and can keep driving perfectly fine. This obviously concerns me b/c the power stearing and breaking is severly affected if it loses power! Has anyone ever heard of anything like this?

A couple of questions:
What could cause this & more importantly, how much does it cost to fix?

 

Could you possibly have a broken motor mount?