bring your car in for service, but be prepared, some places do charge your for just diagnosing the problem by hooking up a computer. i work for a dealership. it is harder than it sounds like. Most of the time the technician needs to recreate the situation and take your car and drive it. I've had to do it countless times, sometimes it takes several hours and the technician needs to get paid. Most places have a flat rate so the customer isn't screwed over if the tech takes a long time.