93sc, auto,........while driving or at idle my rpm gauge drops to zero and the check engine light comes on, then it will go back up and fluctuate and the light usually goes back off. I also feel slight vibration from engine while at idle (sometimes). I believe it may be my coil pack or DIS module. but I'm not sure. I also use a lot of brake fluid, but I never see any leaking on the ground. Could anyone familiar with these problems help me out. THX