How are you able to tell if it's a JSPEC Engine ? I have no TPS Adjustment screw & i'm not sure if i'm missing it or it doesn't come with one originally. This motor has been swapped before from one of the owners I talked to. The previoua owner told me it was a "Jdm Engine". Here are some pictures

 

it doesn't want to idle any lower than about 1600-1700 without wanting to stall out. We've tested that by trying to adjust the throttle stop screw while the car was on & it only idles at 2k the lowest 1700k otherwise it wanted to die. it seems fine and healthy at 2k though.
I've read that ported engines are very fimilar to do this.

 

The JDM TPS has an adjustment screw I tried getting a picture of it probably be easier if my **** wasnt black, if this helps it appears to be the same diameter and thread as the adjustment screw on the opposite side next to the coolant line on top of the TB

 

Yeah I tired using the adjustment screw on the back and it brought it down to about 1500-1600 before it let it go and i had to pick it back up with the throttle & reset it to 2k.
The guy told me he wasn't 100% if the engine is ported or not.
he said it does that because it needs a throttle body sensor but idk if he's 100% about everything he tells me lol.

 

Sorry my point was take the other screw and go to a pick and pull or auto-parts store even Lowes motorsports and find something comparable to replace your missing screw, for what it's worth I believe the NA TBs have the same size screw and thread

 

would it need a spring aswell? I put a screw in yesterday that fit in their but made no difference

 

After the car is warm she idles perfect at 2k. When cold she wants to die unless I hold the throttle for 2-3 min.
One of the previous owners had the same issue with the car wanting to die but for him the car idled good at around 750k rpms (don't remember exactly how much)

 

There's steps to adjusting the idle . It's not just the throttle stop that you adjust and done . The tps is going to be out of adjustment just as soon as you start turning the idle up or down . Which mean you need a voltmeter to get the tps back to spec . You haven't mentioned using one at all . Granted after years of adjusting these things I can kinda get it by ear . But a meter is the only true best way . Plenty of write ups and threads on it .

 

Sounds like a vacuum or metered air leak but really could be any number of things.