IAC restrictor plate installed!

Sorry I don't have any left. There are people selling them on ebay for like $15. Just do a search for "restrictor plate". It is totally worth the money.

You can not get the same idle quaility and range of adjustment with only the screw. Basically if you set your idle right now then installed the plate, your idle would change and you would have to readjust the screw. This means the screw would be in a diff spot to get the same idle speed with less hanging idle and better between shift performance.

I think the throttle responce between shifts is the best thing about these plates. It took the plate and a set screw adjustment to fix my idle. I am glad you like the results and it worked that well for you.

The plate was designed originally for the Mach 1 and it's hanging idle problem. The best thing that I gained from it was the throttle responce. More so throttle responce between shifts!! My exhaust sound changed and my idle got a little better. Over all on Stangnet, I think one person got zero results from installing the plate. Now that I did my H/C/I and SCT tune, the plate is not needed for throttle responce. The chip takes care of that very well.

Have you tried setting your idle with the procedure below:

Begin with a cold vehicle. The idea here is to get the car to a firm cold idle with enough air bleed capacity left in the idle circuit for IAC adjustment.

The idle stop should be set first. Back out the idle stop screw, away from the bell crank arm, until about 1/2 turn past the point where it no longer makes contact (blade fully closed). Using a 0.010" feeler gauge, tighten until gauge just drags between screw and bell crank arm. Remove feeler gauge. Tighten screw exactly 1 1/2 turns. If the screw is very loose, put a drop of loc-tite or silicone on it, so it doesn't work out of adjustment.

Now remove the connector to the Idle Air Controller (IAC) just on the other side of the throttle body. Start the car and allow vehicle to warm for 2 minutes. Give a small "blip" to let it settle. If it is having a hard time staying running you may have to get an assistant until you can get to the front of the car. Now open or close the air bleed screw (CCW opens) next to the IAC until the car idles at 575 to 600 rpm. For guys with aftermarket cams and an EEC tuner, you might want to idle a bit more briskly, say 650 to 675.

Obviously, this rpm range is by what the car and driver wants...IE, no set idle speed, whatever works for YOU.

Turn off the car. Now count the number of turns clockwise to close on the idle air bleed screw. If it falls between 1/2 and 2, it's okay, now reverse it out the same number of turns. Log the number somewhere in case you need it for the future. Reconnect the IAC. You are done.

If the air bleed screw is above 2 turns, it's a good idea to tighten the idle stop screw another 1/2 turn, and then repeat the idle setting. If it is below 1/2 turn, then loosen the idle stop screw by 1/4 to 1/2 a turn, and repeat the idle setting. Be sure to put another drop of silicone RTV on the stop screw if it was disturbed. Reconnect the IAC. You are done.

Just this procedure can fix all your idle problems but this with a plate is perfect. I used the plate before my H/C/I and tune. After the tune all I use is this procedure. Just watch your TPS voltage as you make adjustments.

My chip is a custom tune so I can't really compare it to yours but I learned something about chips and idle rpms when I had mine done. My tuner turned my idle screw all the way down and used the chip to make the car idle at what ever he wants. If you have a pre burned SCT chip, were you asked what idle rpm you were looking for? Maybe your chip is set for one rpm and the iac is fighting it. My car uses the gap at the throttle plate (set screw) and the computer (chip) to idle.
Try getting maybe 1.5-2.0 turns past .010 gap on the set screw and .9 TPS voltage then turn your idle screw all the way down.

I am glad it is working for you, how is your throttle responce between shifts?

There is a learning curve for the computer. I installed a plate on a friends 04 Mach 1 and it would not idle good at all untill we unhooked the battery for a while.