what does code p303 mean

 

What year and engine?

 

2001 4.6 code 125,000 miles could it be a coil or plugs i have no idea where the plugs are on these engines

 

I believe it's the code for misfiring on cylinder 3, you may have a bad seated plug.

 

That is cylinder #3. Third one back on the passengers side.

 

can you tell me where the plugs are an do you need any special tools o i had someone say it was more than likely a coil (thank you for replying)

 

Get a Haynes or Chilton manual before you procede. Here's a picture of coil connector being unhooked. They are the same on your truck. Make sure to clean the hole around the plug before removing it and use a torque wrench to tighten them.
http://www.musclemustangfastfords.co.../photo_08.html