When I start my 190E 3.8 it runs great up until it reaches about 85 degrees C. The idle then goes way down to barely running the car and the oil pressure drops as low as 1 pound when the car is at 90 degrees or higher. Shifting into park or neutral obviously solves the problem temporarily (still only goes up to about 2lbs). I don't want to crank up the idle because its already high when the car is is in park or neutral. The oil level is fine. Any suggestions? Vacuum leak? Air intake? Any help would be greatly appreciated.
1983 500SEC Euro
1988 190E 3.8 Euro