If it runs well, you might just have a pin hole vacuum leak somewhere. Consider pulling the air box off and inspecting the hoses. 4 hose clamps and 4 3mm allen cap screws. Your gonna want a LONG reach allen. Like 1/4 to an adapter w/3mm allen - say 8" long. Edit: and the battery and its box. 10mm... Takes maybe 15" tops.
Maybe a hose wore through??
And check these at the bottom. There are 4mm.
Vacuum leak FTW! :thumbup:
Glad you found it!
Do you record the original turns out for #1 sync?