Given a '94 F2.

Main jets (stock) 135.
Slow jets (stock=38) 40. -stockers were so gunked up that they wouldn't clean...
K&N and slip on...

First time riding it today at the track- Went pretty good, but I found that when I cracked the throttle on the engine would respond a little snatchy, and then have a bit of a dead spot, and then pick up again. I also found when I held the throttle at that position the engine would sound like it was running on 3 cylinders. As soon as I opened the throttle beyond that point everything was peachy.

Any ideas?