VT 5.0 fast idle fault

[BIYTME]

Howdy all,I have a problem with the wifes Vt 5.0 Auto clubby, its just started to idle very high (around2000rpm) and seems to surge between 1500rpm and 2000rpm, started intermittantly and is now getting more common. when the idle fault is present it doesnt seem to have as much power as it used to and seems to upshift very hard but when its not it pulls like a train.Engine warning light came on yesterday on a highway trip but all other guages were reading fine but a quick ig off,sit, ig on solved that
The problem started shortly after an engine rebuild by myself (rebore, new slugs, rings, bearings, reco heads, all the usual stuff) mechanically im good but when it comes to all the wires and sensors n stuff im lost, guess im just old school
Is there anything i can try before i take it to my local dealers and have them rheem out my wallet.

Sorry if i havnt explained everything properly, im new to this Forum thing.... be gentle
Any advice would be greatly appreciated

[Greg Burns]

Maybe it has some cat hair stuck in the throttle body.

[BlackVXGTS]

You may need a new throttle position sensor (TPS). Before you do so, check the TPS wiring to make sure that it hasn't been damaged in any way between the throttle body and the engine harness.