Been chasing this for about a month now. I keep getting DTC's P0071 & PO304. I just put all new plugs and coils in it and it still has a stumble and the same 2 codes pop up. What is going on? and how can I fix this???

 

What year and engine size.

 

It is a 2003 5.4L. I think I'm gonna try to change the fuel injector next.

 

The 1st code is invalid, the 2nd code is cylinder 4 misfire.

 

P0071 Ambient Air Temperature Sensor Range/Performance

 

Couldn't find that code on my dvd, glad you did.

 

Ok, so I just changed the injector and it seems to run a little better but the miss and codes are still there. What the else could it be? What else can cause a misfire on one cylinder (Cylinder 4) besides C.O.P., plug or Injector?

 

Check wire to injector and wire to COP as well. The harness could have a break or damage that is causing intermittent voltage contact.

 

Also double check to make sure the heater hose connection that is directly above the #4 cop is tight and not leaking, that was a common problem with those engines. Make sure the hole is not wet down inside, you will need to remove that cop to be sure.