Spark plugs dying?

[vbomber]

I have a 2000 AU Futura, serviced it at 119-120,000km's new spark plugs and leads, everything running fine, after I filled it up with petrol the next day (driven less then 5km's) I noticed it misfiring? basically if I put my foot down it would struggle (really rough) between 2000 and 2800 rpm, then it would go normal, from the lights don't notice anything but any way it disapeared in a week, nothing wrong since until,

Thursday took the car in for an oil change 125,000km's, also fuel filter, I said the car was running rough in slow moving traffic, they discovered that 2 spark plugs stopped working, first time it happned with the brand (KNG?) , anyway driving home, stopped at few places, but the misfire appeared again, exact same problem as in the first paragraph.

Could it mean that spark plugs are dying again? or another dodgy fuel load or something else, I will take it back Monday but I find it wierd that the problem would start again after getting 2 spark plugs replaced :

[JC]

It could be a dodgy coil pack or leads (spark plugs are the last thing needed to create spark - coils being the first and leads being the messenger).

[51OAU]

yea i would say its just your leads, i had the same problem was only happen in low RPM's changed the leads and was fixed. And it was after i replaced sparkplugs aswell. U mean NGK plugs to?