Ok, so I finally got a little more information then what I previously stated. Here is a recap of all information I have gathered:

Modifications:
NST Crank Pulley
Megan Header
Descendant Cold Air Intake
Tsudo Catback exhaust

Above mods removed both cats, in case that information is necessary. The car will throw on two lights: Check Engine Light, Slip Indicator. The car will kind of bog out, usually only in idle. Idling at 500 RPMs and boost to 700 RPMS on its own, without A/C on.

The code it is throwing is: p0172, which appears to be something to do with a Vacuum Leak, Dirty intake, or something wrong with the fuel.. something, if I'm not mistaken.

Checked the piping, and everything is secure.. so I doubt it's a vacuum leak.. and seeing how my 2011 Scion tC only has 19,000 miles.. I doubt something wrong with the fuel pump or something of that nature.

I've had the intake for a little over a year and, as stupid as this sounds, have never cleaned the intake. Could this be my problem? The car never gave me a problem in the past, up until now.. Should cleaning the intake be something I start with and see what happens?

Thanks for all the information and help

 

Did it start throwing the CEL after installing the header?

 

Do you have something that tricks the O2 sensor cause your #1 Cat is out. Perhaps that device is defective. Also maybe a bad O2 all together could cause this. But I dont think the dealer will like the fact that the Megan Header has removed the Cat...they will blame that.
I sure hope its not the NST Pulley causing these problems. Have you tinkered with any other hoses lately. I once connected a hose wrong on the fuel evaporator thing.
Wish I could be more help.

 

At first the CEL showed up after the header, until I got a CEL eliminator for the header.. then it went away. The CEL only comes on in combination with the Slip Indicator.

 

Do you know what that is? I dont know what your talking about.

 

I popped the same code this past weekend. I have an AEM CAI and an axleback. Cleared the code and all is well, I think is it because of the CAI.