Ford Repair: random misfire cyl 3, luck chris, coil pack

Question
I have had a problem of a random misfire on cyl no. 3 for over a year. I did A full tune up (plugs and wires) but the problem wont go away.when it misfires it only lasts for about 15 sec. which makes it extremely hard to pin point. I was debating on putting in a new coil pack but I hate just throwing parts at the problem.

Answer
Hi DOn thanks for asking. And sorry about the delay.
There is one thing that I want you to try and get back to me with the resluts. Try swapping two fuel injectors, #3 with any other one and if the misfire changes cylinders there is you problem, If Not get back to me and i will assist you further.
good luck
Chris P