O2 sensor problems (long)

I bought my 99 last August with 27k on it and it had been a soccer mom Jeep only. Other than cookie crumbs under the back seat ait was perfect. It ran perfect until April when the check engine light came on. It was running perfect, no skips or missing. I have it tuned with oem plugs, mopar performance wires and NAPA cap and rotor. I got the code read at AZ and it was PO138 high votage on the front sensor. The next morning the light went out and the jeep ran flawless for about 2 months. Then one Friday am going to work the engine skipped just a little. When I left work that day the light came on again. I went to AZ again and the same code. I bought a Bosch OEM sensor ffrom them and put it in and the light went out the next morning and it ran perfect for about a month. Then the same thing, on a friday am going to work the engine skipped just a little and the next time it started the light came on again. Back to AZ and the same code. Had it erased and the next friday, last friday, the engine skipped again on the way to work and the light came on again the next time it started, yep another light and the same code. Is this dreaded friday O2 sensor syndrome I've read so much about, or what. It only had 32k on it when the first light came on and the sensor should last around 80k so i've been told. What are the odds of getting another short lived sensor. They said that maby I should take the Jeep to the stealer, that there may be another "deep" code about a computer failure or short that their code reader cannot pick up. Has anyone else had this problem and if so what should I do? Thanks ahead for any advice or help. Walt from Ky (soon Tucson)