Best deal is to replace cat. If not, cut it out and out a straight pipe in - if you don't have emission testing.

 

as long as you have a "normal" muffler (like a magnaflow or most flowmasters) just not a glasspack or straight pipe, you'll have plenty of back pressure. From my understanding the y pipe is pretty restrictive too and will provide you with some backpressure as well

 

Guess I'll do the straight pipe then, no emissions here in FL.

 

we have very few jobs left here in MI, but thank God we don't have emissions testing! I know that straight piping it seems like a cheap fix, but to me if I plan on keeping and driving the truck for some time, it would cost more in extra fuel than getting a high flow cat.

 

presence or absence of cat should not affect fuel usage. front O2 sensor will maintain fuel trim and computer feedback.

absence of cat might trip a CEL number? along the line of ...cat efficiency low, but even this should not affect mpg.

 

There was a thread a while ago by Drewactual that suggests that this may not be entirely true: https://dodgeforum.com/forum/2nd-gen...-counting.html

 

very good reading. thanks for the link kejobe

 

So, I pulled the O2 sensor off & nothing changed. Still runs like crap. Any suggestions. Fuel pump?

 

Check fuel pressure.

 

bad injector? plugged injector? have you ran the fuel gauge down to e lately? possibley a fuel filter?
you should be able to hook up a code reader and look for pending codes even before the engine light comes on...
cheap code readers can be had for like $20 like the ELM327 bluetooth or usb ones that work with a pc or even an andriod phone ...I love mine ...way better than the $80 reader I bought a few years ago from harbor freight. they even give you real time sensor readings which help when troubleshooting ..