I have a 97 F250 4x4 5.4. it idles rough sometimes and now it shudders and shakes bad on highway. Seems to run good above 3000rpms but terrible below that. Check engine light is on, has been for a couple weeks. Had the codes read and they came up P0133 and P1131. As far as I can tell I should be replacing the Ho2 sensor on passenger side.I would like to know if I should try anything else before I spend the money on an o2 sensor that I'm not positive is bad. Any suggestions?

 

The p1131 is a lean indication but the p0133 is a slow switch indication. I'd look at the O2 sensors. I'd swap the passenger side pre-cat O2 sensors (between the exhaust manifold and the cat) with the POST-cat sensor on the driver's side. On my truck '97 4.2L I'm sure they are the same. See if that fixes it first.

 

check the coils and plug wires first>I think you will find the trouble there!!

 

o2 sensor didn't fix it. Going to check plugs and cop tommorrow. Let ya know what I find out