1998, F-150, 4.6, auto trans with recent fluid/filter change, 210000 miles, duals w/no cats. Ran fine this morning going to my remote shop. When I started it to return home it took a bit longer to start that usual, but not much. As I accelerated it sputtered and smelled rich. I backed off and it seemed to catch but would not shift into high gear. I pushed the O/D button on the column shift to be sure I had not inadvertently deactivated it. Several pushes of the button failed to light the indicator. So it's running poorly and won't shift into high gear. Actually, it seems as though it's not coming out of second.

Likely unrelated, last week I installed one of those Progressive Insurance monitors into the OBDII port.

 

Update: I just went out to the truck and removed the Progressive monitor thing. All problems disappeared!! Hmmm?

 

i have seen those ob2 plug ones cause funky things