I have a 2006 f-150 XL 4.2L V6.

It started here and there sputtering just a little once i'm going up hill. It happened to start this after I had hosed the entire underside of the truck after a snowstorm. No big deal at the time because it only sputtered here and there, and not constant. I thought it might be bad gas or something. Then about 3 weeks later after hosing the underside again when I went to move the truck back into the garage it ran horribly for about 5 minutes. About 3 days ago, in the rain, it started throwing up the P0303 code and runs horribly all the time even at idle. I have just changed the plugs and wires and is still not the fix. Could this be the coil pack? I have read things from egr ports to injectors and am wondering if my problem could be linked to the coil pack.

Please help!

 

Hopefully this is a good test and am not wrongly diagnosing this...

I had one of the old, good, plugs hooked up to the #3 plug wire and cranked over the engine. It had no spark at all. So I am right to assume it is more than likely a bad coil pack?

Any ideas?

 

Easy test. Move coil 3 to another cylinder and see if the missfire follows. If it does not then you can try an injector. If still the same cylinder a compression test will need to be done. EGR stuck open will affect all cylinders.