So, I switched my EGR valve sensor back to the original, and now I am getting the correct voltage. I drove the truck down the highway to let it warm up. It still has a bad hesitation/backfire when up to temperature.

My EGR code has went away. I’ve driven it several times and the only code that remains is code 41 saying there is a problem with the o2 sensor, or the truck is running lean. I replaced the o2 sensor about a month ago.

What steps should I take now?