Multiple problems 7M-GE

[StillChasing1]

I recently returned from a deployment and pulled my car out of storage.

I started it up and it ran just fine (with the exception of a rough idle) right up until it got warmed up completely.

i have massive power loss, the exhaust turned beat red from cat #2 back to the muffler, and it is having serious idle issues.

I drropped the cat thinking that was a problem but it was in perfect condition.

I tried timing it but i cant get it into perfect time, i am not sure if im missing something here but i set it TDC and hit it with a timing gun get really close but every few times around the notch jumps and comes back. What could cause this and is the timing issue causing the problem with the exhaust?