As crazy as this sounds, I had a very similar problem with intermittent idle and after replacing the IACV and TPS and after having ordered the intake gaskets, I decided to give one last shot at trying to find the obvious before I tore into my intake.......which lead me to find that the culprit was actually the vacuum hose that comes off the Fuel Pressure Regulator. That little $.25 hose was the reason my VX would idle all over the place. When I discovered it, it was chaffed and cracked at both ends, all I did was lop off about a 1/4 inch off both sides and reconnected it to the FPR and the upper intake plenum, its been running fine ever since - Hope that helps!