I have 06 outback sport, 156k. Car recently started "surging" when idling or at low speed. The first time it occurred, it felt like a car had tapped my rear bumper. It feels like the car might stall or shut off. I just recently had new alternator and new battery installed, both boots on cv joint replaced,150k tune up, timing belt installed at 120k. I'm wondering if this could be fuel pump going out? Is it safe to drive to dealer for repair or should I have it towed? Thanks!