So something I've noticed with my evo 8 when at a stop if the heater is in my idle drops to just below 800 rpm and man does it shake like a **** what could be the cause of this while driving it's just fine just when I come to a stop it is blowing hot air so that's working but I can't figure out why the idle doesn't come back up to normal..
Maybe alternator or battery not sure which one it would be

 

PS I have torque solutions motor mounts on all 4 maybe that's it but if the idle would come back up to 900ish where it normally is it would not shake

 

Is your AC on also along with the heater or is it just the heater? If your AC is on then you can fix your RPM drop by upping the RPMs in ECU Flash.

 

Nope AC isn't on first thing I checked well at least I don't think it is my AC dash light doesn't light up when I click the button and I don't notice any difference if I click it or not

 

Light could be out. Check under the hood for a running compressor.

Anyway, if you have a tune, this is something that commonly gets messed up - engine rough or dying with A/C on.

 

You need to calibrate your IAC and idle.
warm up your car
- use evoscan 2.5 to "Activate the SAS MODE"
- check the IDLE, if its less than 800 use the BISS screw to raise it a bit...

 

Will do can't do it till me tatrix comes next week and my new laptop but I'll be jumping into it as soon as it gets here