Car stalls when depressing clutch when coming to stop light

[usurp]

Hey guys, I have the Fast EZ-EFI system installed and pretty much finally got it working right (i think). Only issue left to sort is that the RPM drops dramatically if I'm coming to a traffic light and I take my foot off the gas and depress the clutch quickly. It's as if the IAC motor can't switch on fast enough and 1 out of 5 times the car would stall when I had RPM set to 900. I've now increased idle RPM to 1,100 and the car doesn't stall anymore since the IAC can turn on before car stalls, but I still get this huge RPM drop and I can't figure out what would be causing it.

Does anyone know or have a theory on what it could be from?

 

[Faster Behr]

I have the same system and have had to troubleshoot the same issue.

What is your TPS voltage at idle in the information screen? The system doesn’t like it to be 0.0V, so if it is then I suggest preloading the TPS by rotating it around the throttle shaft slightly and then running the TPS and IAC calibration from scratch. Mine is 0.2V at idle and 4.3V at wide open throttle. Hope this helps.

 

[usurp]

Mine is 0.3 and I think 3.4 when open. After posting here I actually got in touch with FAST and to my surprise they actually responded pretty quick and with a solution that sounds like it should solve it:

The first thing I would look at is the IAC number in Live Data at a warm idle. With a manual transmission and the type of problem you are having, I will adjust the throttle screw until the IAC number is bouncing around between 5 to 10.
That will give the engine a bit more air past the throttle blade where the IAC doesn't have to "work as hard". Ideally, the IAC shouldn't have to catch the engine if there is enough air coming through the main butterfly.
Then be sure to re-calibrate your TPS in the Advanced Menu if you adjust the throttle screw any.