When I started my '99 528i one morning, the engine started misfiring and the check engine light came on. I stopped at a local coffee shop and when I restarted the vehicle, the engine ran fine. The codes said there was a misfire in #5 and #6. I changed the plugs and cleared the codes. Ran fine for two days and then the misfires started again. Went to my local BIMRS shop. They read the codes but couldn't reproduce the problem. Paid about $350 for a fuel injection and fuel induction service. Car ran fine for two days but the problem reappeared today. After stopping for lunch, the car ran fine and the check engine light went out. Any suggestions? Thanks very much.