[Jackpine]

I'm not the expert here, Bill is. But, I'll offer my thoughts.

Level 3 already has advanced timing to run 91+ octane gas. I think your advance of 1 point (and sorry, I don't know if this is really degrees) was WAY too big. The manual suggests a 0.5 increase for each octane number increase, so your timing was set up to the 93 octane level.

I'm surprised that put you into limp home mode, especially so quickly, but I can't think of any reason for the other changes to cause the problem.

I know I tried advancing the timing by 0.25 once (since we live at 2500 feet, and you should be able to advance the timing some for increased altitude) and it caused my idle to "wander". (I've said I advanced it 0.5 in other threads, but that was because I couldn't remember the smallest possible adjustment increment - which is what I actually tried). So anyway, I think the truck is VERY sensitive to timing issues, and that's where I'd put my money. Be interesting to hear what Bill thinks.

- Jack