latief, your friend must be a soft touch. Why would anyone pay for repairs that didn't resolve the sluggish peformance. Encourage her to take her 1991 300E back to the MB dealer and insist that they resolve the problem. If it were me I would never have paid for the oxygen sensor, distributor cap, rotor and spark plug replacement if the problem still existed. The fuel filter seems like a possibility; but a qualified, experienced tech at a MB dealer should be able to diagnose a problem and fix it before even considering returning a customer's car.

Replacing the rear subframe bushings to pad the bill and not resolving the sluggish performance is disgraceful. I would be having a heart-to-heart discussion with the owner of the dealership.

__________________
Fred Hoelzle