w126 84 500se revs up and down no power!!??

[bru123]

hello! i have a 84 500se and i would very greateful if someone could give me some advice. My problem is that my car starts fine but it has no power
when the car is cold and i try to rev the engine it hesitates instead of
accelerate, when it warms up the engine revs up and down and fuel pump
makes sound as if it is over working -------what could it be?


Thank you