hey guys, I just fixed a 95 c 280 with the same symptoms. is the vacuum pump in the trunk cycling? there is a vacuum block in the right rear side of the engine compartment under the black cover that covers up the hand held computer hook up. 1st check to see if it cracked. 2nd if you have a vacuum tester, remove the glove box & the lower panel under it. behind the crossbar reinforcement is the vacuum switch over valve. remove the lines & test which one leaks vacuum. mine was the center vacuum element located under the left loer panel under the steering wheel against the heater box.