could be broken tps...
i had d same prob... changed afm, changed aac, changed ecu... nada! still idled high...
yup, it was d bloody tps... when i pulled the tps socket towards me, the idle dropped to normal...
temporary, i used a 15mm bolt & put it in between the tps socket and the intake pipe connecting hose dat leads to the throttle body... well, it's ok now ;-)
dunno 'bout u, mine is d rb20det...
hope this helps...