The truck came to my shop with you can running very rough only when warmed further up. It had been tuned up less than 6 months prior. I did notice an innovative new alternator appeared to be installed and not just by me and my friends. I remembered the customer had told me he was on vacation a month ago together it installed because it failed while on a trip. I inspected each primary and secondary ignition system for signs of failure. Strategies checked out fine. I hooked up my scan tool to retrieve any service codes, there where none. I ran both a “key on engine off” and “key on engine running” self tests with my scanner. No codes where retrieved. Next, i went to data stream mode and observed the critical engine control inputs and outputs. All readings appeared normal except for your upstream O2 sensors