'96 LX 450 CEL with multiple codes

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Dec 18, 2006
Been driving with CEL on for a couple of months with no noticeable repercussions (I know, bad of me :() but the ol' gal seems to be running just fine. Registration is due so I finally decided to check the codes and came up with the following codes:
p0300 - Misfire detected in 2 or more cylinders at the same time.
p0302 - (cylinder No. 2) Misfire detected in each cylinder.
p0303 - (cylinder No. 3) Misfire detected in each cylinder.
p0306 - (cylinder No. 6) Misfire detected in each cylinder.
p0420 - (Bank 1) Catalyst deterioration :censor:

Searched forums and found more suggestions with DO's and DON'T's than I could count. One that kept coming up was a suggestion to clean the MAF sensor (but NOT to touch the connectors). At this point I'm lost. Any recommendations? Could these be multiple symptoms for a single issue, or have I got several major issues to deal with?
You need a copy of the factory service manual (FSM) as it has an excellent trouble shooting guide for all the OBD-II codes.

The P030X codes are all related to misfiring. Since more than 1 cylinder is misfiring, it is a random or general misfiring. The P0420 may also be related to misfiring.

The top trouble areas in order of highest probability are:
Igntion system
Injector (only for a single cylinder misfiring code)
Fuel line pressure
Compression low
Valve clearance out of spec.
Valve timing
Engine coolant temp sensor.

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