Any particular spots to check? Leaks before the throttle plate should not have an impact on idle in my (admittedly limited) understanding of how fuel-injected engines work. I have taken a couple of the hoses apart in my quest to inspect the water pump and they're all fastened together nice and tight as far as I can tell.
The "hard" stutter makes me think it's a misfire and not a vacuum leak or other idle-seeking behavior. But for $350 I'll spend some time checking for anything obvious.
