I have recently had the EXACT same issues... Here is the solution that i have found. First of all I replaced the intake gasket which was a pig of a job!!! I had a crack on the inside of the manifold just behind the throttle body, which make it difficult to diagnose since it was near impossible to spray carb cleaner in that area... after the replacement, idle went down to an unconsistant 900-1200rpm, much better that the 2000+rpm! after throwing a slew of parts to solve the rest of the problem (IACV,FPR,TPS) nothing helped... i even tried unplugging the power steering pressure sensor with no help... and i was getting very frustrated!
Here is what i did to get it idling at the perfect 750rpm... while the engine is idling (assuming it is hopping up and down) unplug the throttle position sensor, your idle should immediately drop to a consistent 700-800 rpm. Your check engine should be on & TOD Check light should be flashing. While your engine is still idling plug your throttle position sensor back in, then shut off the engine. Walla! smooth idle after that! Your Check engine light should stay on for 5-10 key starts then the check engine light should go out on its own. There will be a stored code after that (P0122) even though your CEL is off. i havent bothered to erase it since my idle has been perfect for over a month now and i dont want to mess with it if it is idling fine! Try that solution, it much cheaper than replacing the TPS, FPR (fuel pressure reg), IACV (idle air control valve) and the intake gasket or spending an hour of your life unplugging a PSP (power steering pressure) sensor. If you do replace the intake gasket which i would recommend if you suspect any crack, torque the bolts to 13ft/lbs NOT the recommended 18ft/lbs. Unless you really want to replace the gasket in a few years, I wish that task on no one! I had to end up taking a hack saw to the EGR tube and welding it back. there was no way i could get a wrench to turn on the seized collet nut that connects to the EGR Valve on the manifold. GOOD LUCK HOPE THIS HELPS to all who read!!!