alternater takes plug wires or coil?

[Fullagar]

ok heres the deal.....a friend of mine that is a little car stupid bought a 96 firebird 3.8L and i told him i would do the work on it (trying to keep as many f-bodies on the road as possible) and he just had to replace the alternater on his car, now it backfires and misses. i have already searched this and am pretty sure that he needs new plugs and wires. the only thing that i have a question on is that when in park or neutral if he revs the motor the tach gets to about 4400 it starts to bounce. this seems like a coil problem to me. any help on this would be much appriciated.

94 Camaro A4 K&N fipk and pacesetter cat back
93 Z28 M6 M29 K&N fipk, accel 300+ ignition, and flowmaster cross flow muffler

[black98V6]

I'm pretty sure the computer lowers the rev limiter when you are in neutral or park. you are proably hitting that..