Howdy folks, I just finished replacing my cylinder heads and getting everything back together. I let it warm up at idle (normal temp range) for about an hour, shut it off and let it cool down, then repeated. I test drove it and it felt stronger (for a 4.0 OHV) however, after getting a couple miles down the street, from a stop, it had some hesitation.

My question, could it be the O2 sensors? I replaced them about 5K miles ago with OEM part (motorcraft). Through research I have found some say O2's DO need to be replaced after doing a job like this. Is this true? I know I am reaching here but is it possible to pull them and if they are gunked up, take an abrasive like a wire brush and clean them up? I just don't want to sink another 120+ dollars in O2's if I don't have to.

Thanks in advance for any helpful advice!