I asked about the brakes pedal, because one of the reason for revving up when put to N or P may be that, when your mixture is too rich and you select with brake pedal depressed, booster increases air amount and engine, having more fuel in the mixture, revs up.
I do not have my computer at hand to give you part number for the gas pedal lever spring, but if you call MB dealer, this should be no issue.
Others may name other reasons for revving up too, I guess.
Speed at which shifts are made is often the question of modulator pressure adjustment. This procedure is described in Technical Manual and in many posts o n the forum. Again, difficult for me to provide links right now. Just double check the units and values of pressures in sources and in posts, I think there was a mistake in one of the sources.
It is done via solenoid-modulator lever rod adjustment (accessed through the opening in the transmission tunnel in the passenger's footwell area) and/or adjustment bolt at the modulator. It is a relatively simple procedure (I did it myself, so it must be), but you need a gauge with a banjo connection. I made the little tool to turn the regulating bolt myself. When I took the car on the lift where she stood on her wheel - this was the easiest set up.
Others may be of more help here and better advise.
