Need Help!!!! I have a 2003 Ram 1500 Hemi 4wd Quad Cab. I was getting a P0441 with no performance issues. Then while driving I started losing power and got a P0300 and then got a P0308. Now, the only way to keep the truck running to keep my foot on the gas, I try to let it idle, then it will just stall. When I am giving it gas to keep it running, it is running very rough with a very strong exhaust smell. I have looked the codes up and know what they mean, but just can't figure out what to fix.

Here is what I have done so far with no success:
Checked vacuum lines
replaced plug wires
replaced plugs for cylinder 8
replaced oxygen sensors
tested fuel pressure which was okay

I think I may have a bad catalytic converter, but don't know if it would be causing this problem.

Thanks,
Brian