Went to track today, did about 23 runs.

The car seemed fine for about 10 runs, then it started missfiring every run once the rpms got over 4000 or so. It sounded like beeeeeerrrrrrrrrrrrr babababab beeeeeeeeeeeeeeeerrrrrrrrr bababababa beeeeerrrrrrr.

After i shut it off to take a break and look at slips, i let it cool down a bit and it didnt miss for about 2 runs. IT seemed to not do it after i took breaks which makes me think it is heat related.

I never usually have this problem and i didnt have it on the way home (just easy driving)

My car is tuned up so the cooling system works good, i got new ngk tr-55 plugs @ .050 and taylor wires.

I am wondering now, what could this problem be (Opti?, Coil, ICM?)?