[W126 Coupe] Odd behavior at cold start

[Richard Hesek]

Hi,
  I may be doing some diagnosis on my idle control/ fuel mgmt system soon.
Upon start up when cold, my engine surges between 500 rpm and 900 rpm every
2-3 seconds. Smoothly up and down, but not a steady 900 like it always has.

Also, upon cold startup, the engine gags, or almost stalls, as though the
cold start injector is not working.

I suspect that will be my first item to look at but I wondered if this is
familiar to anybody?

Rick Hesek
Northboro, MA