1992 500SL rough idle

[Don911]

I have intermittent very rough idle. The car hesitates, then clears when I accelerate. EGR etc ?

 

[stats007]

Distributor based R129s suffer from voltage tracking issues and water ingress. Best to check these as well as leads and plugs. Throttlebody may need cleaning. Idle control valve or EGR as you say.

 

[Don911]

Thanks....forgot to mention that it is generally good, but a bit sluggish when sarting to accelerate at city speeds, but always much worse after I have slowed down from highway speeds.