Idle speed is certainly low. I'd get the Tach fixed and get the idle dialed in where it should be. Low idle + cold engine = unhappy results.

I'd suspect you also probably have air in the fuel system. Check the usual suspects - primer handle, leaky hoses, lift pump, etc. Seems to help a lot of people diagnose problems by replacing the return line with clear PVC and looking for bubbles.

__________________
Current stable:
1995 E320 157K (Nancy)
1983 500SL 125K (SLoL)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Gone and wanting to forget:
1985 524TD 167K (TotalDumpster™) [Definitely NOT a Benz]