Also, just for future reference, never use KBB. Its weighted for the stealerships, and is always high.

Edmunds.com gives you the most realistic, IMO, and NADA isn't bad sometimes, although other times it tends to be unrealistically high as well.

 

According to edmunds.com...

Assuming your truck is fully loaded with everything not listed in your signature (power driver's seat, sliding rear window, ABS, etc. etc.), Edmunds tells me that the private party sale value is about $3000, depending a little on your region.

Having a mechanical issue like that drops your truck from "Clean" status to "Average" status. If you fixed the misfire, it'd add at least $900 to its resale value.

I personally would keep chugging along and fix it, but up to you.

 

the cat will rob power big time and i believe it can hit just one cylinder with a miss fire. my sisters truck had a partially plugged cat and she had intermittant miss fires. if you have a welder you can cut it off and try to run it. without the cat you may get an o2 sensor code but if you have your power back and no miss fire then you know you need a cat. if it doesn't fix it you can just weld it back on and either do further diagnosis or just off load it.