Idle issue on start up

[Rubikahn]

Had a bad O2 sensor on the truck. REM was throwing O2 code fault lean. I tried ordering OEM, and NTK sensors. Got an email stating my order was being canceled the next day by both places I tried. So I broke down and bought a Crown O2 sensor. Got home from work and swapped it in. The threads on the old one didn’t look bad so I didn’t chase them out. Screwed the new one in and I’m not sure if it’s seated all the way. It’s definitely tight and I didn’t want to crank it down anymore. I can still see threads sticking out. Started it up and look underneath. I didn’t see any smoke coming from that area but I’m not sure an exhaust leak at the O2 would be clearly visible? Shut the truck and went in to eat. Came back out about an hour later to go out and now it’s idling really weird at start up. It’ll idle really low almost to the point it’s gonna die. Then it’ll go normal. Then it’ll idle really low again, almost die, then go back to normal. After it does this twice it seems to idle and drive fine. If I shut the truck off it does the same thing all over again. The old O2 was not causing this issue. I did run 4oz of  Seafoam through the brake booster vac line last night and poured another 12 oz into the gas tank. Let it sit for a half hour and then took it for rip on the highway for about 40 mins. All was good when I got home last night and when I used it today before I swapped the O2. I tried uploading the video of what it’s doing but the file is too large. Pics of new O2 and the one that came out. Also noticed the old one was ceramic but the new one was metal 🤷‍♂️

[Rubikahn]

Got the issue squared away. It was a bad O2 sensor or a brand the truck doesn’t like, lol. Add the Crown O2 sensor to the list of brands that do not work. Crown sensor on the left. I took a pic of the part number of the new NTK O2 in case anyone needs one anytime soon. Ordered it about a week ago and it finally came in from O’Reilly’s. It is idling good after start up now and stays that way.