To the best of my knowledge, an 02 Jeep doesn't have coil packs, they just have a coil, and a distributor, because they use the same engines they did 10 years earlier. Because of that, I would say it's not the coil. What I would venture to guess, is to check the plugs, wires, distributor cap. Do a normal tune-up on it, and see if that fixes the issue. If that's not it, then it could be a bigger issue, like stuck fuel injectors or a damaged cam or valve that causes the valve to not shut completely.