sorry for the delay - had to step out -
There definitely aren't any fuel leaks, and it doesn't act like vacuum leaks (i.e. running a marshall fuel pressure gauge - pressure set at 61psi, with quick throttle, pressure jumps rapidly, etc.).
I'm not familiar with a wideband, but aside from the Jackson, everything else is stock.
I've had to play with fuel pressure and timing - and of course using the stock air box - to get rid of the nock. the FMU is installed properly (reviewed it about a dozen times), all else appears to be correct as well.
I'm wondering if the altitude/pressure drop is greater affect than the thinner air at the intake. It certainly doesn't perform to JRSC quoted dyno graphs. We dynoed before, hit 163hp @ 8.5K - it now has ~ 30-40% gain until it hits 6K, then stays on linear slope hitting 175hp @ 8.5K. From the dynos, it appears the VTECH is kicking in correctly. I questioned Jackson about the FMU performance - they say it's working properly. I've also heard their FMU is not very good.
Thanks for any ideas.