In late August I replaced the original O2 sensors on my Jeep just for the heck of it. I ordered Delphi sensors and shortly after on startup the Jeep would stumble and run poorly for a couple minutes, when driving it would stumble and cut out but after a couple minutes it would run fine. Saturday it was doing it the morning I was taking it out of town and it finally set a CEL for the upstream O2 sensor. I put the old sensors back in and I haven't driven it but I started it and it runs fine. Would still like to put some new ones in again though. I'm returning the Delphi sensors. Rock Auto has Denso, Bosch, and NTK (which might be OEM? Not sure). Any recommendations?