Are you sure it's the wiring that's the problem? The idle control board is known to develop solder faults (cracked joints, poor connections, etc) and cause some truly random idle issues.

If you're going full EFI, why are you bothering to troubleshoot it now?

__________________
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]