Fuel Composition Sensor need some help

Hello,
This is my first post here, nice site btw.. I have a 2000 Flex-Fuel s-10 and am having a world of trouble.. Here are the codes I am pulling

P0178 - Fuel Composition Sensor Circuit Low Voltage
P0179 - Fuel Composition Sensor Circuit High Voltage
P0141 - HO2S Heater Circuit Bank 1 Sensor 2
P0300 - Random/Multiple Cylinder Misfire Detected

I was originally only pulling the fuel sensor codes but am now getting the others as well.

My truck is acting like it is either running rich(i do smell gas), lean or is not breathing well. When the gas is floored it just falls on its face, and cannot seem to get over 45mph...

Now my question is: Would the fuel comp. sensor be causing this problem? Do the "symptoms" seem to be like what woudl happen if the sensor is bad? I just want to make sure this is what it is before I buy the sensor as it runs about 400 bucks shipped... Any advice will greatly be appricated...
-Matt Graybeal

PS I changed the fuel filter about 200 miles ago.....

I would suspect a clogged cat. converter, backing up the exhaust and creating back pressure. Sure hard to diagnose on here though.

I had thought of that as well but just figured the computer knew best.. Is there anyway to see if it is the cat, like a shade tree method? Thanks again for the help,
-Matt