I read my check engine codes and I got the following:

#30 - split air solenoid valve
#38 - solenoid valve (accelerated warm-up system)

I still have all of my emissions, so I'm not sure why I am getting these codes. I have some idle problems (it does not want to idle at 800rpm, it usually stays arround 1.3k, but you can force it down with the clutch while not moving). I just thought my idle was because of vacum leak that I can't find... Can any of the above(#30 & #38) affect my idle?

My car is:

1989 GTU
Mods:
JDM Tii engine/trans (~9.5 peak psi)
N370 ECU
S5 FCD
2.5" downpipe. hi-flow cat, rest is 2.5" straight exhuast
255 Walboro
etc...

 

Because something is wrong with those systems. That what an error code means. Read the troubleshooting section in the FSM Fuel chapter, where it lists the test procedure for each error code.