Looks like the upper plenum brace gets removed and from reading on MUD some long ratchet extensions will get you there from underneath. Sounds like the VSV can be checked pretty easily per the FSM. Need to check for dry/rotting vacuum hoses. Not sure what/where the vacuum modulator is, maybe I'll find a picture of it or figure it out once I'm under there.
Oh, this thread has good pics of how to reach the VSV (and shows the long extension):
Maybe I should move it to the fender like this guy: