[cmyk]

We are going to need some more info before we can really be of much help. With what you have provided we are all just throwing our guesses into the hat.

You said no CEL, but have you actually scanned for codes, or are you just going by the fact that there is no CEL or half engine light on currently? Not all codes will trigger an idiot light (or trigger one right away). You have COBB so use it to pull codes.

Also, I don't think I saw where you answered my question about the idle: Is the idle surging while this is happening?

This kind of info would help with diagnosis.

Also, you mentioned you just had some coding done by an indy shop. Does the option not exist for you to take the car back to the indy who last touched your car and let them know that you are now experiencing this problem? It looks like you recently replaced a lot of parts on the car. My initial wild guess would be that something was installed incorrectly.