Chuck, once again thank you for your wisdom and willingness to help!

I think you are absolutely correct in your statement regarding two unrelated problems. I also discovered that the WUR is holding vacuum after the Air Housing Guide repair. In my previous post I think I also mentioned that I have replaced the vacuum lines with the exception of the round plastic vacuum check valves which are next on the hit list.

The Thermostat was changed out approximately 3000 miles ago. I have checked the antifreeze mixture which registers in the norm. This week the Thermostat will be changed as well as flushing the Radiator and checking on the flow. Additionally I have also replaced the cap on the reservoir and checked the timing which is dead on. The Car goes to the shop this coming Tuesday.

I have made several attempts to adjust the mixture based on your previous guidance, but the idle will not smooth out in either direction and actually becomes much worse. That was what was making me suspicious of the Cat as I don’t believe there were any other components we had not tested. As soon as I have the Car back from the shop I will follow your instructions and DC the O2 sensor and try adjusting the mixture as per your post.

Thank you again! Hope all is well with you and yours!

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82 380SL 41K miles sold, 98 SL500 44K miles, 13 C300 4Matic, 14 CLA-250 4Matic