E300 Surging Problems

I have a 1997 E300 that has had a reoccurring surging problem. The car has 55,000 miles and has had the intake resonance flaps replaced 3-4 times. This is what the dealer says is wrong every time I take it in. Is this normal? I have a 83 240D also that is much more reliable. Anyway, I bought the car used but it was a Starmark certified vehicle so assumed it was well taken care of, and of course it's a Mercedes. Has anyone seen this or have any advice for me? I have not been successful with getting the dealer to admit there is a problem. I also plan on contacting MB direct very soon this is not the only problem this car has had it seems like it is always in the shop.