dhworkin I feel your pain. I too have a Vortec engine with Edelbrock performer intake, tbi and headers. I also purchased a chip from Harris and my engine idles rich with a catalytic converter. I have tried fuel pressure up to 20 psi and down to 15 psi with no difference in behavior, so unfortunately, we both may need to start over with a decent tune before going in circles. Best of luck.
Owl