I ended up loosening the manifolds and pulled them back a half inch, sounded beastly buf revved right up. Cut out the cat and its totally fked. Sucks the magnaflow cat only lasted a year but its under warranty

 

might check out your 02 sensors and see how they are functioning. might not be throwing a code.

 

You probably did this whilst the heads were off...however...Have you checked down the intake, past the throttle plates? Is the floor of the plenum swimming in oil. if it is, the plenum gasket is blown. Also, pull n clean or replace the intake air temp sensor...I've discovered that they're an accomplice in crime in many idling and gas guzzling problems. Known a few 2nd gen Dodge 5.2/5.9's to have this problem. Many times, it silences the intermittent hiss of death as well, if the IAC valve doesn't.

 

It was oily, but no standing oil. I replaced the gasket. The gasket was a pita to remove. I already had a felpro head gasket set, timing chain and water pump sitting in the garage for about a year now so i put em on. Oreilly exchanged the cat free , just gotta weld it on after work and im g2g.