P0420 & P0430 Codes Help!!!!

[Feeze]

I have been searching on here looking for an answer, but am now @ wits end! My Vehicle is an 04 X5 3.0. Currently with just over 128,000 kms (80,000 miles)

Last August I purchased a 21' Malibu V-Ride (boat) in Ann Arbour,MI. Towed it back to Regina, Sask. (Approx. 24hours) She towed the boat no problem. Shortly after returning my SES light came on. The vehicle seems to run perfectly fine, still lots of power & no noticeable change in MPG.

So far this is what I have done:

-Changed the Plugs
-Replaced Coolant Temp Sensor (on bottom rad hose)
-Checked the DISA, MAF, hoses do not see any major issues
-Replaced O2 sensors before the cats, had the codes cleared, SES came back on
-Replaced O2 sensors after the cats, had the codes cleared, SES came back on

I though I had finally had it cased on this last one, but the SES light came back on again this morning. It seems the SES light returns around the same time after I have the codes cleared.

If it the cats, would the vehicle still run as well as it is?
Do I need to look further into MAF boot, sensor & components?

The only other hiccup was a couple times during the winter when it was really cold my temperature guage shot up like crazy. Pulled over, shut the vehicle off for a couple minutes, restarted and the problem went away. That is why I changed the CTS.

Any help, suggestions would be much appreciated!