O2 sensor

My Trooper's mileage seems to be getting worse. It has 120K miles on the
clock, and AFAIK oxygen sensors have never been replaced (been driving it
since 98K). I'm thinking about replacing O2 sensors - how long exactly are
those supposed to last? Also, Alldata shows sensor's pigtail being kinda
round, but all sensors I've been able to find online have rectangular plug
type. Does that mean I'll have to splice the wires and re-use existing plug?

Advice appreciated!
Peter

Hi. I was curious if you got an answer to your question (how long o2 sensors last).

I have a '93 Trooper with the original O2 sensor. It just turned 180k and the O2 light came on as I have read it does every 90k. I am trying to decide if I should have it replaced or not. Any suggestions?

Some of the quirks with my Trooper:

1. I have surging problems when first starting in the morning or after it has been sitting for several hours. It doesn't matter if I let it warm up or not. It does goes away after the initial take off. No one seems to know why it does this. Any ideas?

2. I also notice what I think is pinging when I am driving at an idling in town around 40 mph and push on the gas a little. It doesn't matter if it is summer or winter. Any one else have this problem? Do I need to run higher than 87 octane?

3. Finally, my engine has a ticking noise. It has always had it as long as I can remember (120k), but it seems to be getting worse now especially after I drive on the road for several hours and then drive into town. My wife even asked me what that ticking noise was, so I it must be loud. I have heard it might be related to low oil pressure.

Don't know if any of my problems are related to my O2 sensor, but I thought I would see what anyone else had to say.

Thanks for any advice.
Justin