so for ****s and giggles i removed it again this weekend just to see if there was still a difference after everything i've done. and wouldn'tcha know it, there still is a difference.

2 new o2's as well.

what else could be causing the lack of power when the o2 is in?

What size piping you have ? Removing it could be letting more out netting more power ?

Do you have the deathflash ?

piping? as in exhaust? well up until after where the cat used to be i have a jegs offroad y-pipe. not sure about the rest.

not sure about the death flash. from looking around it looks like the 99's were prone to have it. but wouldn't it still be bogged down regardless if the o2 were in there?

Is it running pig rich with O2 installed? Do you have a scanner or code reader that allows you to watch (or plot) O2 readings live?

nah no scanner handy. i bet my mechanic has one that i can use. anything else i can try in the meantime?

I got the P/n(part number) off my 99' ,and checked it on a chrysler pcm flash availability chart.This will tell ya any re-flashes it has or hasnt had...Its a long list..PM me if you need more info

If there is nothing wrong with it, it will give the appearance of running better for a while... You're forcing a fault, and the brain hasn't figured it out yet.. you're most likely simply operating in closed loop.. which means richer, which means smoother..

how can i rectify said closed loop?

Should have said open loop.. you can't.. the engine closes loop when conditions are met... Namely, the temperature of the o2 sensor reaching operating range where the pcm can trust the data it shares.

Maybe all the loose crap from the previously bad cat is stuck in the muffler.