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...is there another part involved like a sensor?


Yes, possibly. There is a Throttle Position Sensor and an Idle Position Switch plus a Fixed SAS adjustment procedure.

However, if you intend to disconnect the ISC, there's no need to do any further diagnosis. If you want to find the problem and try to fix it, begin with a check of the ISC.

Good luck,
Frank

'89 [color:"white"]G-Raider[color:"white"] [color:"black"]Supercharged 3.0L, MegaSquirt 2, lockup A/T, 2.5" exhaust, 172k, Cibie H4s/Oscar SCs, Hella Micro DE fogs, Cobra CB, Superwinch hubs, LSD rear/Aussie Locker front, Bilsteins, Lifeline AGM, Rust-Oleum