what is wrong too much gear and tire????

[5.O STANG]

Ran at the strip wed night and was very pissed after. ive got an 04 gt 5spd with an exhaust leak from the exhaust manifold or h pipe im not sure exactly sounds like a v6 ,410 gears 315 35 17 with nitto drag radials 17x10.5 wheels and the car weighed 3700 when i arrived at the track. I only weigh 150 but i just moved and had lots of stuff in the trunk. Also right after my run I was going for the next run when my car shut off for no reason could this be a bad alternator??? I got scared so I didnt run again. Anyway my BEST run was a 14.66 at 96.7mph with a 2.0 60ft. I Never let of the gas, power shifted at 5100-5300rpms and they would jump up to 5900rpms then it would go to the next gear. Is it possible that i have too much gear since my car is stock? Are my tires too big? Was it my shifting that sucked? Was it the weight in the trunk? Was it the exhaust leak? Was it the launch? ANY SUGGESTIONS?????