How often do you change out your spark plugs/leads?

I have a groupA coil and a set of "fordmotorsport" leads that are a few months old. My car has developed a bit of a misfire when boost is around 13psi?

 

should last for years mate, id check dizzycap rotor arms and plug gaps first

 

Thats what I was thinking. The plug gaps were done when it was set up. I'm gonna give it a once over 2moro.
It just seems odd that yesterday it suddenly developed this misfire.

 

Sometimes plugs can go bad, you usually notice is it immediately when they are fitted or within a very short time. As above check cap/rotor and if no faults found change for another set of plugs.

 

Managed to have a good look in the daylight today. The dizzy cap at some major crusty build up on the points. I was almost certain I Checked in when I fifted my new splash gaurd afew weeks ago. I must have not lol.

 

With regard to an ignition problem ialways cange plugs and leads together and gap them accordingly at the same time, also change to distributor and rotor arm if the car has one, quite often you can damage the leads if you only change plugs or vice versa