Thanks for the response Bob. I too suspect vacumm leaks. The vacumm hoses in the engine compartment are pretty cheap on fast lane (sold by the meter) so perhaps I should replace them all and see what happens. Shotgun diagnostics, I know, but cheap.

Where is the warm up regulator located?

Thanks again for your response. Mike

__________________
'90 300SE 298k
-300K and it gets put into retirement.
'80 300D 255k Purchased new by family in 1980.

Had a:
1973 220 (gas)
1980 300SD
1992 400E