CEL triggers only while cruising

[Madison Mehlhose]

As long as it all works and runs OK, and the fuel trims stabilize as the computer re-learns...you're set.

I still have some concerns about spark knock and the EGR valve/lack of catalyst back-pressure. The obvious solution in that case would be to slap an aftermarket catalyst back in place.

Have you run into this problem or has someone else?
I think the intake vacuum alone should be within the control window of the ECM to compensate for small changes in back-pressure.