My 1994 mustang has started to have a poor idle, like it will jump to 800RPM, then drop to 400RPM, and stall out. And while driving it will cut out completely, like i have no power at all. it will do this for 20-30 seconds then come back. Sometimes I here a buzzing sound coming from the right side of the car. I ran a KOEO and KOER test and got codes 172(02 sensor fault/lean) and code 332(Insufficient EGR flow detected.) I have had the 332 code for a long time and I'm sure it's because i dont have one of the egr vacuum lines connected. I have cleaned the MAF, TB. What could cause this, and what's the fix?

Mods on my car are LT headers, no cats, flowmasters, CAI, 70mm TB. I have had these mods for over a year.

 

replaced IAC with no luck.