I recently replace a new coil pack and new cat on my 96 miata. However, everytime I drive on a hill, the car starts losing power, then it slowly loses acceleration and the engine stalled and shaked. It is almost like half of the coil pack wasn't working or the car was overheat (I am not really sure about this one). After 5 minutes, I can start my car again. It happened consistently, and I am not even pulling on the engine. I don't know what's wrong with it. I towed my car three times in a few months because of this. Need some ideas and suggestion on this. I really want to drive my car. Thanks for helping.