W124 Warm engine idle woes

[romsey4]

Hi all.
This is my first post since buying my 1989 300ce late last year. I have read a few threads on this topic but still unable to narrow down my problem. The car starts first time everytime, but when it reaches its normal operating temp it develops this rough uneven idle that fluctuates between 400-800rpm ish whilst in gear. This causes it to die sometimes when coming to a stop or changing from drive to reverse. Ive checked the idle valve and this is clean and operates when I put 12v to it. I can unplug the valve and the problem goes away but it idles to high at around 1000rpm. Also if I remove the fuse from the ovp it idles evenly but is still to high. Ive checked all the vacuum pipes and they are good. Would my next step be temperature sensors?

I would appreciate any advice

Thanks in advance

 

[grober]

There should be a fine idle adjust screw/stop somewhere- Like the automated fast idle bypass valve it bridges the throttle plate by a separate passage- maybe try adjusting that? Note its not the mixture screw which its not advised to adjust without the aid of a exhaust gas analyser.

 

[romsey4]

Hi Graham. Thanks for replying, I will have a look for this adjustment screw, didn't know there was one.
Cheers Lee