2 months ago ce light came on.Had codes pulled and got p304 p305 p300 and an o2 sensor code.I changed plugs and wires and coil and changed o2 sensor and truck ran good for about 1000 miles.Now ce light back on and I got a code for misfire on cylinder 4.Besides doing a compression check any other ideas?It's a 2003 3.0.

 

check the catalytic converter on the side with the bad misfire

 

Thanks for the response.I will check out the pre-cat.I was right there when I replaced o2 sensor but my truck was cold at the time.I hadn't considered that.