A new cat should solve the HC level, you can get them ready to bolt in for about $75 at autozone, or $55 and you have to weld on your old flanges(cut them off the old cat), or new ones.

The O2 sensors when they fail normally richen the gas mixture so not to harm the engine.

You are either getting too much air from an unmetered source(i.e., a vaccum leak somewhere, intake manifold leak, crack in the intake tube), or not enough gas from clogged fuel injectors or filter. I would check all of your vaccum lines see if they are cracked or split around the fittings. If you don't see anything obvious, you can check them for leaks by using a small propane torch by cracking the valve a little and holding it near the vaccum lines, if the engine speed increases you found the line that is sucking in air. Next replace the fuel filter, I would also retorque the intake plenum bolts. This would be the cheapest places to start. If it is still running lean, pull the injectors and have them cleaned and rebuilt, should run about $225, then replace the intake manifold gaskets.

Check the FSM at the top of this forum and see if there are any pointers for running down the lean problem. You need to get this fixed soon since running lean is a quick way to burn a valve.