I am getting this code on my 1999 5.4 Expedition. The plugs were changed last year by Ford and some coils that looked bad were changed. #3 was not one of the that were replaced. I just want to cofirm that #3 is on the passenger side, 3 back? How hard would it be to replace the coil myself? Looks like they are at Checkers for $42. I found some directions on it. Any tips? Thanks.