I decided tonight just to open up the driver's side of the engine compartment and "see what I could see". Gave me a chance to look over the intake "bellows" (far, far better design, far more robust than the M54, this being the N52 in my 08 X5. The CCV hoses looked very nice as well. I still shook on all that I could get to. All were good. Thought maybe there was a "throttle control valve" to clean like on my wife's M54 but I did not spot one. Two DISA valves, front and rear, fancy!

Always bearing in mind... what did I do that changed things from the way up North when the engine ran strong and perfect for 1550 miles, and immediately on the way heading south with an -empty- trailer, it had no power at all, bogging down, on the highway.

The only thing I touched was the heater control valve. I replaced the defective one for a good used one. That's it.... Ready???

Well...since buying the vehicle I have noticed the workmanship has been shoddy on engine bay repairs. A screw missing here and there, a cover not on correct, etc. Well it turns out WONDER BOY...whoever this mechanic way, decided it is FAR, FAR TOO MUCH WORK TO TIGHTEN THE INTAKE TRACT CLAMP on the throttle body. So he just pushed it on the throttle body and called it a day. Yes...the screw was extremely difficult to tighten from under the intake tract but again just took time and patience.

I bet when I was wrestling out the old heater control valve that has a mount of only 2 pins it rides down on, and having to twist it by the hoses to get at the lower hose clamp screw, that I cocked the LOOSE intake housing on the throttle body just slightly. Just enough to introduce a slight air leak. Not enough to throw a code, but enough to introduce extra air down below the MAF? I won't really know until spring when I head North, but I bet I got it! This would all make sense regarding the above facts. (: