I just finished fixing the idle on all of my friends DSMs, so you may want to listen up.
First, take that retarded block-off plate off your DSM, trust mitsubishi on this one. Un-loop that coolant hose, and put the hoses back in the stock configuration.
The FIAV is great, it causes the engine to warm up faster, so your engine will last longer. Cold pistons = piston slap. The FIAV does not cause F*cked up idle, no matter how much you want to believe it.
Your ISC is dead, you need to throw it away. It also has ruined the driver control circuitry on your ECU.
SO now you have a ruined ISC and a damaged ecu.
Second, you need to buy a new ISC from
www.dsmisc.com $140
Third, you will need to send your ECU into dsmchips.com -or- the DSMLink guys so they can fix the ISC controllers. $50.
If you dont believe me, take your DSM out for a drive, get going about 30mph, let off the gas while in Nuteral. Your engine should go down to ~1000 RPM. Now press on the brakes, at a complete stop, wait 2 seconds and your car should kick down to ~750RPM. This is stock behavior for a stock working idle control system.
I learned all of this from reading VFAQ BTW.
Oh, and mitsu temp sensors work great, or your car does not turn on, there is really no in-between with them. They wont be "just a little messed up"