As your fella is a proper hondata dealer, why not just take it back to him to sort out? That's what I'd do (assuming problem wasn't there before hand).
Are you sure you have no vacuum leak? As you said you replaced the intake manifold. If there is a vacuum leak the car hunts/bounce also to 2000 RPM.
Just use some brake cleaner and spray at the vacuum hose connections. If the car revs higher you have leakage on that part
Ok everyone the revving was back with a vaginace tonight it would just hold the revs to 2k rpm when out of gear and then once i put the car back in gear it would come down if i was in the low rpm wile in gear driving .
Really has me to the point where i dont want to drive the car .
Tryed looking for vacuum leaks and i couldnt find any. So iv now replaced tps, iacv and renewed the throttle body gaskets and its still there .
I know it sounds ludicrous but have you taken the car for a good spirited drive at all? I mean prolonged revs through various gears? It normally helps you know, obviously try and do it somewhere safe and not with other cars/pedestrians about. I find getting it through the gears especially 3rd and 4th really help clear any issues.
Try taking a look at the thermal idle valve on the head, these can some times get damaged when fitting the RBC.
Its a little plastic T piece to the right of the intake manifold, has a hose running to the center of the intake manifold and to the intake hose.
I think this is what makes the car rev a 2000 rpm when started from cold.