[W126 Coupe] W124 Idle issue

[mavris2 at comcast.net]

Hey guys,

My 93 300ce Sportline just had the wire harness replaced.  I got the car 
back and well it is having idle surge problems now. It did not do it on the 
first day I got it back.  It started acting up on day two.  The car did not 
have this problem with idle prior to this. But then again I dont drive the 
car maybe 200 miles per year.  I know thats my problem right lack of 
driving! HA

They replaced the wire harness and OVP, clutch fan and serpinteen belt. .  I 
have since taken the car back, but am wondering what could be causing this 
fluctuation in the idle?  Im just not looking forward to them calling as 
saying its "XYZ" and it'll cost $$. This is a very good shop with a mechanic 
of 18 years experiance.   But Im just baffled at this.   The car has only 
got 84K on it.

Any ideas?

Thanks

Jason