my 2 front o2 sensors are bad got code reader and both running lean i dont really notice a difference in performance and gas mileage was 2mpg less so instead of paying 250 for both of them and another 100 to get em changed at the time i decided to wait it out and ran some emission cleaner thru car engine light turned off till about a week ago.

now today i start it and notice i'm idling at 500-700 rpm doing 75 on highway i'm getting 2600rpm which doesn't seem good to me. How hard are the front o2 sensors to replace by yourself?

Anything else that can be causing the idle to go that low? o2 sensors went bad about a month ago...