1997 Nissan pickup rough idle
I have a 1997 nissan pickup with a 2.4L 5speed manual. I've been have problems for a while and up to now i've replaced the fuel filter, checked the fuel pump, replaced spark plugs, spark plug wires, and replaced the distributor. I've also had the catalytic replaced. I was told that when you change the catalytic you should change the oxygen sensor behind it too, but i didn't. Now it idles kind of goofy. It's lopey almost like it's missing. The RPMs at idle hop around from 900 to 600, but when i'm driving it's fine. If i just rev it up to about 1400 RPMs it seems fine. I was wandering if the rear oxygen sensor could be doing it, and if it's not then what??