Sorry for the long post but I think the back story on this is going to be important. The question is, does this sound like something that a tune can fix?

Back story... A year ago I had 2 coils fail at the same time and the raw fuel that dumped into the cat ignited and melted the platinum in the cat. I drove the car for a couple weeks like this (after replacing the coils) and there was a vibration but only under load. If I drove around in sport mode it would go away but mostly because of the higher RPMs in the sport program. FYI, this is a CVT car. After a couple weeks I replaced the cat with a test pipe and installed a spark plug non-fouler in the downstream o2 sensor bung to avoid the CEL from the cat efficiency but I still have the CEL. Unfortunately, the vibration remains and I've changed the plugs twice, most recently they came out indicating a lean running condition but Torque Pro never shows the a/f ratio above 15 except under closed throttle deceleration where it hits as high as 29... Or that may be the upper limit on the gauge in Torque.

My thinking is that the missing cat is doing as expected and allowing more exhaust flow (and therefore more air flow) which is causing the lean condition which is causing the vibration. Does this sound reasonable? Would a tune possibly be able to fix the vibration and lean condition? The only codes I've ever seen are about some intake manifold flapper position but I haven't seen that one in months and other than the vibration it seems to run very well.

Any ideas? Thanks.