2000 XJ 4.0L Engine P0171 Code

My 2000 XJ with a 4.0L engine has come up with a P0171 code. I changed the plugs a few weeks ago, as I had a occasional stumble. Just prior to changing the plugs I got a P0171 code. Changed the plugs, reset the code and all seemed fine. The XJ has just over 177000 miles on it. The wife has been driving the Jeep for a couple of weeks now with no problems and no error codes. Today we went to go to a tractor show and shortly after getting on I-75 I got a check engine light. Came home and took our Grand to the show. When we got home I checked the code and once again I had a P0171. I think the O2 sensors are the original ones that where in the vehicle. I was wondering if the upstream O2 sensor could be getting flaky. Outside of the P0171 code being on the XJ seems to run fine. I don't want to keep driving it though and risk engine damage. Open to any and all ideas and any test procedures I should try. I did test the fuel press and it is right in specs.
Thanks,
Bill

Check fuel pressure under load (driving down the road) and if it's up to spec, then change out the O2 sensor.

O2 sensors have a service life of about 150,000 miles. New O2 sensors would be routine maintenance.

Be sure to buy NTK O2 sensors, Bosch O2 sensor have been known to cause some drivability issues.

sidewaysstarion said:

Check fuel pressure under load (driving down the road) and if it's up to spec, then change out the O2 sensor.

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Tim_MN said:

O2 sensors have a service life of about 150,000 miles. New O2 sensors would be routine maintenance.

Be sure to buy NTK O2 sensors, Bosch O2 sensor have been known to cause some drivability issues.

Click to expand...

What they said.