It's also possible the timing chain tensioner is faulty and needs to be replaced. That was the case with our 1992 300CE. To properly seal the timing chain cover it's best to use the MB black sealant that comes in a tube that works like a caulk tube. It's a great product.

The engine hesitation could be due to a faulty Oxygen sensor. When was it replaced last?

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Fred Hoelzle