Idle too high

Krem12 said:

Have you adjusted the throttle stop on the TB?

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The little screw by the spring? Yeah several times. I have read that that screw is pretty irrelevant considering the computer does all the adjustments. Also moved the TPS as that is an option with this TB and that did nothing. I’ve read that if I unplug my IAC and it fixes the idle problem that it means I have too much voltage to the TPS but idk how that helps me fix the issue.

Summarized/Corrected Base Idle Reset Procedure (sbftech.com)

Try this. TPS just has to be within a certain range, doesn't have to be .98v or whatever.

Get a multi meter on the tps. With Key on engine off, check the voltage. Start the car, TPS voltage should be exactly the same. If its rises without the throttle being touched, replace. Years ago i had a TPS sensor become heat soaked and would randomly raise the voltage, car basically acted like it had cruise control.

Screw is relevant, it sets the base idle. If that screw is adjusted that it allows the car to idle at 1500rpm, the cars going to idle at 1500rpm. IAC cant remove air, only add.

1995Beast said:

I replaced my CAI from a beat up BBK to a new SR one and a stock throttle body to a 75MM SR throttle body.

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This is likely your problem. SR is an awful brand and it wouldn't surprise me at all if their TB is causing this issue. The BBK is superior to SR any day. You only have an Edelbrock intake and long tubes as engine mods so the 75mm TB is probably way overkill imo and is also possibly why you're having this issue. Stock TB size is only 58mm so a 65mm would have probably been perfect for your application. You're essentially overcarbing the engine with air. Krem12 would be better qualified to weigh in on that though.
Throttle Body Size Guide | Factory Mustangs - LMR.com
Check the CAI for any gaps or around the MAF. Though usually it does, sometimes cleaning the IAC doesn't fix it and replacement is necessary.

Thanks for the responses. I wont be able to mess with my car for quite some time now as I just left for training but I’m leaning towards the issue being the huge change from 58mm to 75mm…. I will try what you suggested Krem12 but idk why my tps would be heat soaked now when it was working perfectly fine on my old throttle body. Maybe my throttle response wasn’t as good as I thought before 🤷‍♂️ If the size difference is the issue then I hope American Muscle will let me upgrade and pay the difference for BBK. Not holding my breath.

I ran a 75mm TB on my car with only bolt ons and an intake. It does reduce your "driveability" a tad. For every degree the throttle butterfly opens, more airflow can flow. You'll get to a point where part throttle can supply the engine with enough air for "full throttle" if that makes sense. Is it a big deal, meh not really imo.

The TPS is just something to check, gave me headaches for months trying to track that down.

My bet is still on the base idle screw or unmetered air entering the system (vac leak somewhere upstream of the MAF like @cobrrajet67 said)