Why did you replace the O2 sensor? Did you actually diagnose the problem or just try throwing parts at it? If you just throw parts at it, it's a sure fire way to get frustrated.

Are there any exhaust leaks? Vacuum leaks? What do the plugs look like? Do they show a lean condition or a rich condition? I know I have asked all of these questions already...

As far as putting a carb on it goes, have at it, but don't expect the rest of the truck to get along without all of the inputs/controls that it has with the stock setup.

 

Maybe a back pressure problem in the exhaust-plugged cat?

 

I replaced the o2 sensor bank 1 sensor 1. Thats what the code said. It was the only code that it gave. The plugs show its running lean.

I cant find any vacuum leaks. I think there might be a small exhaust leak but wouldnt that make it run rich?