hmm... that 2500 rpm is weird.. try closing your idle screw.. it's on the TB, it's a slotted screw. Turn it clockwise to close it, see if your idle goes down.
when it went up to 4 grand did you rev it, or was that it going on it's own?
post up pics of your intake manifold and throttle body and vacuum connections, maybe i can shed some light onto that.
I'm going to go take some more detailed pics of mine and upload them for you... it's a ZC but should be similar.