Got a misfire on my 2wd saff between 3750 rpm and 4250 rpm.Changed the plugs for pp8's and gapped them 28 thou' then gapped them 25 thou' but still no joy.Sometimes it doesn't do it other times it does,plugged it in to my mates crypton tuner to make sure the coil and leads etc were o.k. and seem fine.Took dis cap off to check and rotor arm but all appears fine. Car is also running a stage 1 chip,never had a misfire on it before at all in four years of ownership so this is really strange to me.Any ideas guys?