Original owner 2001 Taco

Good day, thought I'd poke around in here concerning an issue with my wife's pride and joy V6 Prerunner. It has 240k on it now, and I've done all the maintenance and repairs/improvements myself. I come from the adage that you cannot over maintain your vehicle, but you can definitely under maintain it. That said, in 22 years she has only been towed once for a starter failure. Still has the original ball joints, tie rod ends, CV joints, etc. She gets 2,500 mile oil changes, and the remainder of the fluids annually. Spark plugs get changed every 15-20k, and she strictly drinks Premium fuel. The battery (lead acid) has only been replaced 2 times to date. Replacement items are strictly AC Delco when available and affordable. Even having lived outside in the AZ desert all its life it still gets mistaken for a new truck with the original gold paint.

Anyway, on to my problem. Just did the 3rd cam belt (w/ idlers/tensioner, water pump, thermostat, radiator hoses and accessory drive belts). Did front crank and cam seals and valve cover seals, replaced original Crank position sensor, Cam position sensor, and igniter. Replaced original fuel pressure regulator, fuel injectors, IAC control, and MAF sensor. She also received her 2nd replacement set of new coil packs and wires. And I inspected and cleaned the throttle body which only had a little build up and miniscule bore wear and shaft movement.

On start up she fired up quick, but raced at 1800 rpm. I allowed her to heat up completely but she only slowed to 1700. Started searching troubleshooting through my manual and then online. Everything checks out to be 5X5. Could find no vacuum leaks. The only time she slows to 800 rpm is if I detach the IAC wiring plug. Of course that triggers a check engine light, but she idles normal. performed reset TPS procedures multiple times (although TPS was replaced 75k ago) Tried driving her 65 miles as many said here that that cured their issue to no avail. Wondering if for some reason there may not be a signal going to the IAC valve to trigger low idle since it slams shut when disconnected? IAC valve operate as designed when off vehicle, and resistance readings are right in the middle of spec's.

She starts quick, runs perfect except for the idle speed, and throws no CEL unless I disconnect the IAC plug. Any idea's appreciated.

 

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