It's usually the wire...

Look at the wires closely, and see if they melted onto the exhaust. Tape it up, and secure it away from the exhaust system.

You need the o2 sensor. Without it, the computer can't tell how to regulate the fuel mixture, and will run like total crap.

"A young man who does not have what it takes to perform military service is not likely to have what it takes to make a living." - John F. Kennedy

Proud owner of an 88 Montero (with a blown engine).