P0420 + Running rich.

So it's been over 7000 miles or so since I've had a periodic P0420 code pop up. A while ago my bank2 (driver side) Pre-cat started making a little bit of a rattle noise when the engine is decelerating, lately it doesn not do this, hmm, lol, I'll accept the fact that it is probable defected my cat after the pre-cat now.

I've also come to notice that this might not be normal, my exhaust is a bit misty in appearance and has an odor of fuel. Even after letting the engine idle and warm up for 10 to 20 minutes, it's still misty and fuely. If I give it throttle and jump the RPM's up, it produces more mist/smoke, above 2000 rpm's the exhaust looks clear. The smoke isn't black so it's not burning really really really rich, just a bit rich. I'm almost certain it's not burning coolant, that would uberly suck. Doesn't burn oil.

I need to get nissan looking at it, dealer is about a few hours away from me, but what I can do myself, I will, it's all fun to me and a learning process anyways.

I changed the non-pre o2 sensor on my driver side exhaust, from what i was reading a while ago, that o2 sensor is more prone to go before the pre-cat sensor. This resolved nothing.

I have an OBDII Elm 327 code scanner and I have ScanXL software. Does anyone know if ScanXL will be able to give me o2 sensor readings to tell if maybe my pre-o2 sensor is faulty ?

Cleaned the MAF sensor today, read online that many suggest alcohol. Parts store was closed till monday so I couldn't get a can of MAF cleaner. Was very nice to it, inspected before re-installation, all looks good.

Engine runs strong, seems to accelerate just fine, happy with it... but idles a bit roughish/vibrates a bit after warmup, nissan and many on the board say this is normal.

Any help is appreciated.

Thanks guys.
-steve

PS:
I know I have other similar threads in the past while, but I feel I've got to re-word things and update my new findings with a new thread as I try to solve my issues.

31K Miles, factory exhaust with 4 catalytic converters. No performance mods, no ECM software mods.