oxygen sensor

Guys, my 2000 expedition(4.6 engine) started running rough about a week ago. The service engine light came on at the same time. I had the fuel filter replaced(my best guess). The rough running is a lot better but still has a rough spot when the engine is under a load. I was told it might be the oxygen sensor. I'd like to replace it myself but don't even know what it looks like or where under the hood it is. Any help would be appreciated.

Hi, sounds to me like you have the failing ignition coil problem, especially if it runs normally at steady speeds and when decelerating, but starts to shudder when you tip in the gas pedal. Look into having the codes read at an Autozone(freebie), the code will tell you which of the eight cylinders is misfiring, then its a simple matter of swapping a coil from the suspect cylinder with another coil from a good cylinder. Erase the existing code(s) and road test till the check engine light flashes again, check to see which cylinder is now setting the latest code: if it is the original cylinder then the coils are good and the problem is being caused by a spark plug or injector or ....... If the new code points to the cylinder that the suspect coil was swapped into then that means that coil really is bad. If you need more info, let me know, Good Luck, Nick

Thanks for the reply. That makes sense to me and I'll do that. I did'nt know that about Autozone. Thats a great bit of information to have since Car Care Clinic told me they would do the same thing for $65. Thanks a lot.

My parts department stocks 4 new coils and boots, so we won't have to be running to the Ford dealer all of the time. Coils fail, frequently.