Just closing the loop on this thread. I have no clear answer, but this problem has seemed to resolve itself. This chain of events is kind of strange, but here it is.

A few months ago while travelling, I left the X5 with a shop for some work at their leisure. Thermostat, coolant reservoir and spark plugs among that work. On return I found an increasing misfire and the growing "hitch" in the drive train- experienced while de-clutched rolling to a stop. The only codes I got indicated an open thermostat. Since this was new, I checked the fitment of the electrical connector to the thermostat housing.

I brought the X5 to a local shop to inspect the flex disc and support bearings. They found no issue with these , but did replace a worn tie rod end, and verified lube levels in the trans and transfer case. All good.

This was a few weeks ago. On return, the misfire and drivetrain issues are gone. I think the misfire can be associated with re-seating the connector at the thermostat, but don't get the drivetrain issue. Anyway, just wanted to close the thread.

Thanks

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Chief

2004 3.0 6 speed manual