ok so ive had a couple 300sd's but i have one that use to run just fine but now it takes forever to build power and you have to hold it to the floor to get it moving on down the road....its had all new filters and the trans is new...when the car is in park you can rev it just fine but once you put a load on it it just goes to hell .....anyone have any ideas what it can be....turbo is building plenty of boost also thanks

Clean the banjo bolts out on the exhaust manifold and IP. They get full of carbon and cause low power. Also make sure the hard plastic line from the exhause manifold to the valve on the fire wall isn't broken. My wagon's was broken when I bought the car. Once it put it back on properly I had all kinds of power.

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