Hi all

Could anyone advise on the following (93 190E 2.0):

Sometimes, the engine rpm will be about 1,200 to 1,500rpm. It occurs occcasionally jsut after I have shifted gears (automatic) from D to N or R to N. Otherwise the rpm is normal which is between 750 to 850. I took the liberty of changing the idle valve controller but it does not seems to help. What could be the likely causes? Does the transmission play a part then?

Thanks.