[blykins]

Lippy is spot on here. A wide-band won't do you much good with a camshaft with a decent amount of overlap. Your camshaft may not be that big as far as .050" duration goes, but most slower ramped hydraulic rollers will be fairly large as far as advertised duration goes, which increases overlap. Could very well be why the A/F ratio was showing oinky rich at idle.

Plug reading is your best friend. You can get a lot of info from how the tip of the porcelain looks, how the base ring looks, and how the strap looks, but you also want to look *down* into the porcelain and see what color it is down inside. If you're a doc, then you should have access to some pretty good tools for close inspection.