my 190E is running hot, at a stop it climbs to the mark above the 80 degrees C mark. while moving at 35 its falls back to 80. what could be the problem.

its also idling high at 2000 RPM's and it fluctuates from 1500 to 2000 rpm occasionally.

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Current
2006 E320 CDI, 57K bought at 67K "Liesl"
1986 190E 2.3-16, 198K bought at 56K "Brigitta"
1987 300TD (Chuggin Along), 292K "Friedrich"
1995 E320 Wagon, 200K "Louisa"

Past
1987 300SDL, (sold) 125K, bought for 1$ "Kurt"

High temp is probably the magnetic fan clutch switch, a temp sensor located at the front of the block (red?) that has failed. Check if the engine mounted fan spins up when the engine idles and the temp rises. If not, remove the wire connector and "short" the pin holes with some insulated wire and see if the fan clutch engages while the engine is running.

Your idle issue could be many things . . . vacuum leak . . . bad idle controller valve . . .