estate320

I have not found a post on my problem. When giving my 2000 E320 Wagon any amount of gas I loose the center dash vents on the a/c until I either let off the gas or get to a coasting position. I assume it may be a vacuum leak but would like some help to locate the issue if anyone else knows what is happening. This is my first MB, love the car more than my Volvo S80 but worry about repair hell. Any help would be appreciated.