I have a 94 S10 4.3 W. It has been running very rough and almost stalls at idle and the exhaust smells really rich. I have cleaned the EGR,replaced plugs and O2 sensor. I dont have any check engine codes. Tried the paper clip trick only got a code 12. A friend tells me to change the CAT. What do you think I should do.Only have a 30 day temp tag to get it fixed.

 

With the information you mentioned it sounds like you may have a leaking fuel pressure regulator, nut kit, or spider. You can do a quick check by pulling the IMTV and looking down into the intake. You will be able to see if there is any "washing" on either the passenger side (fpr leaking) or driver's side (nut kit leaking). Also you may see fuel pooling in the bottom. Just be gentle pulling the IMTV since you need to reuse the o ring.


You could also do a fuel pressure test if you have the gauge?

 

^^dito^^