...Dave

I wish I could help but I have the same annoying fluctuation (on my '90) - you can hear it but its not enough change to register on the tach. I've not done anything about it yet and I am WAY behind you in skill level/knowledge so I'm listening (reading) real closely...

Good luck. If I accidentally trip over a possible answer I'll make sure it gets to you...

Kevin

__________________
"Dangerous with a wrench...and not smart enough to know it"

Stable (in order of acqusition):
'84 500SL, 280SEL (Euros)
'77 280SE. '90 560SEL
'79 450SEL 6.9,
'95 C280 (totalled by daughter 8/07)
'81 280SL (rescued) '88 300CE
'86 560SEC '95 C36
'01 CL55

DD's: '04 S500 4Matic (SWMBO)
'04 F150 Crew