Keep us posted. It could be the tune, or a combination of mods, or both. Hopefully, I stand corrected on my previous comment.
I can't remember what day I put the MPT tune back on, but I suppose it's been close to a week. The code has not returned. See that? I bet I just jinxed myself!
I will be taking her in to have the alternator tested, as I've read this will sometimes generate the same code for reasons unkown, and I've experienced one or two hard starts as the temp's have cooled this past week. Last time this started happening my battery croaked. It didn't illuminate the idiot light or throw any codes though. And considering my GEM burned up last year, I wouldn't put it past more gremlins being in the electrical system(s).
I figure the alternator is worth checking, as I've read about it in too many threads to ignore it. But for now all's well and I'm having loads of fun with gobs of torque!