My car has been running great at normal driving but here lately at tip in and harder than average throttle, basically under boost, the car sputters, backfires, and misses. And the boost actually fluctuates, any suggestions? I believe it to be the leading coil pack....

 

Exactly what mine did when leading coil went bad. $135 from ray at malloy mazda

 

The factory service manual shows how to test it.
http://www.iluvmyrx7.com/1993_factor...ice_manual.htm