What do you guys think is the cause of this?
 

I just bought a beautifull 88' 560SEL & I really couldn't be happier. The only problem that I've come across that concerns me is that the enigine revs way too high when it is in neutral, about 1750 rpm. I am confused because the car idles fine when in drive, but whenever you put it in park or neutral, shift to reverse, etc. the rpm's shoot up. So if I have it in drive & shift to reverse, the engine goes up to 1750rpm before it engages, making the car lurch violently. This can't be good for the trans., so I want to get rid of the problem asap. Any help would be much appreciated. Thanks in advance.

>>>okay, I did a search under flairing and it seems that this is a problem with the idle control valve. Now what? Is this a matter of replacement or adjustment? how much will this part cost, and can I do it myself? I am new to mercedes, but I am fairly good with cars.
--sorry for all the questions!

I would not know the price in the US of A , but I changed mine last week, got it for about USD200 from Dubai. As for repairing the unit I have seen some posts in this forum ,something about soldering a purticular joint inside the unit
Sorry, not being much of a help!:)

ttt

There's a slight chance that something may be disconnected under the hood. I doubt it, but check that all the little plugs and wires to the right of the alternator are connected. Sorry I'm not being too technical when describing this, but I recently changed spark plug wires on my 88 420SEL and had to disconnect something to run the wire. When I started the car, I forgot to reconnect this little plug near the alternator, and the car idled at 1500.