I was on my way home tonight when my grande made a loud pop sound about a dozen times. When it popped I lost power. Then, I came to a stop sign and it stalled out. I took out the plug and it looked fine, so I started it back up and the rest of the ride was normal, though I did baby it a bit. What could have caused this? I am concerned that there is a serious problem, but don't want to jump to conclusions.