Misfire at 4000 & 5000rpm?

[grand-one]

My 4.0 Chimaera has developed a slight misfire on full throttle openings at approx 4k and 5k rpm. On part throttle loads its fine, only does it when pushing the loud pedal all the way. Any ideas what may cause it? Ignition coil going, air leak, or something else?

[Mark.]

I had the same, around town and stuff it was fine but as you say, giving it some beans a mis-fire. I had a split in the HT lead going to number 8 (think it's 8, one in front of the driver). Replaced leads and all fine.

[Quietlybonkers]

May not be relevant......but I suddenly developed a slight roughness on startup and a bit of a misfire, and it was the number 8 plug lead (offside rear) that had popped off, so I was running on 7 cylinders. It wasn't noticeable when toddling, only at start-up and on full chat. Nothing wrong with the lead in my case, it had just popped off the spark plug

[Mark.]

Oh! I can remember the cylinder numbers!