Hi all,

I posted some months ago about my 2000 S-Type surging at idle, and running lean. I took it to my regular shop, and they found oil inside some of the spark plug sockets. So they replaced the valve cover gaskets, a breather hose, the expansion tank hose, one direct ignition coil, and five coil boots.

It did work--for about 6 weeks the car ran perfectly. Then it started acting up again, and now it's basically back to where it was last winter--rough idle/surging, and hesitation while accelerating through 45 MPH.

Any ideas on how it could be fine for some time then go back to the previous state? Does this mean that another gasket is leaking oil into the coils? Maybe the IMT o-rings issue?

 

I ended up replacing the valve covers plus the seals. I think they warp over time.
And the bottom windshield seal may alow water under it and onto the back of the engine. You should use sealant under the plug well covers on the V8. You can put black sealant under the top edge of the window seal. Tape it down until it dries . Be careful when removing the duct or packing tape.
PS Fist blow out any water or oil in the plug wells!