Today I was taking my brother for a ride and when I stomped the throttle, it performed greatly, and I as I went into 2nd, it started backfiring and hesitating severely around 4500+rpms. As long as you drive it below the 4500 range, it drives just fine all day. It never did this before as long as I've driven it. No engine noises. I cranked it this evening and I heard a extremely loud clicking noise under the hood, and it was coming from the tfi coil. It made a noise in the past but its now extremely noisy! Its a msd blaster coil. The timing has been checked and adjusted to different degrees and it has no change in performance. Plugs are new and so are the wires. Any suggestions as what it could be? Like I said, as long as I drive it below 4000 rpms, I can drive it all day with no problems. Check engine light is not on. Thanks.