Just happened last night. Stranded my wife for about 20 mins. Got the "reduced power message" then after a couple of restarts it seemed to run right and she got it home. Looking at Mitchell service info it appears the 3 most likely culprits are: Throttle body, MAF and MAP.

My question is: Do any of you with a similar vintage Lucerne with Series III 3800 ever run into this issue (code P006 and If so, what was your fix?

Thanks
Max

I would check for vacuum leaks if none try cleaning the MAF sensor if you have a scan tool that will let you see the tps and even better if it will graft it with the engine not running slowly press and release the gas pedal while watching the graft it should be a smooth signal without any drop out in the signal if it is bad you should be able to see it on the graft

A vacuum leak is not going to put it in limp mode and this throttle body don't use a single sweep linear TPS.
Keep your eye on it. It would be nice if you had a scanner rather than just a code reader.

Thanks for the info, yes, I would like to have more than a reader.