BMW Repair: 99 528i wagon...changed plugs...disconnected neg bat. terminal, now it periodically has power drop, vanity mirror, negative battery

Question
I recently had a misfire in my 99 528i wagon. the check engine light was on. i replaced the plugs. before i did so, i disconnected the negative battery terminal. after replacing the plugs & reconnecting the battery, the misfire was gone. the check engine light remained on since i had not reset it but then a couple days later i was driving the car on the freeway, got off & stopped in a parking lot.  after attempting to drive away the headlights, dash lights, and radio started to short in and out on power. I turned the car off and restarted it and it was fine, and the check engine light had reset itself & has remained off. this same power issue has happened twice since then. both times i turned off the car and restarted and it was fine. one time that it happened i think i noticed the abs kicking on and off also.

Answer
With the limited info i have, it sounds like you have a bad ignition switch witch is very common on that vehicle.When it acts up try moving the vanity mirror cover on the visor open and shut to see what happens, if it affects the the problem you have then it definitely needs the ignition switch.. hope this helps.     Thanks Nathan