5.7 hemi idle and backfire
The error codes you had listed overheating and such on the o2 sensors. I can't recall exactly. I'm guessing the o2 sensors prolly look fine but are fouled up. With an engine with 300 miles, I'm guessing it's a lot of short trips. I'm hoping your doing some good break in procedures. I believe your issue was with one o2 sensor on the side that has the fouled plugs. The computer prolly went to open loop and dumped fuel thinking the AFR was out of wack..
If it's working then drive the **** out it. It the o2 continue to foul, then look more into the issue.
@dartman 440 I alwsys use OEM o2 sensors. Same reason....there pretty much the best. But a Bosch/Denso will work as well as that's who makes the OEM's. On the swap the downstream o2 sensors are not needed. I'm going to be using upper O2's on my TTI headers.
Riddler