380SL Fuel Pump Replacement Causes Rough Idle & Other Problems?

[ezrider]

380SL with 106K miles needed fuel pump replaced due to low output, cold start problems and it was very noisy. Fuel filter had metal bits in it too. Engine had excellent idle and tranny kickdown at moderate speeds worked fine prior to the pump replacement. After the pump was replaced the idle is now very rough and the car does not downshift at moderate speeds like it did before the pump replacement. I have looked for a vacuum leak and can't find any.

What could be causing these problems, it is directly related to the new fuel pump as that was all that was changed

Thank you.