Chrysler PT Cruiser Engine Problems

I'd be looking at spark, that's more often the cause of misfires. If the plugs and leads are in good order, I would be looking at engine sensors, their connections and the wiring.
 

Belts perish and stretch over time and need to be replaced even though the mileage is low in your case. We couldn't establish a recommended time, from mechanics or Chrysler dealerships, but I would suggest it would be worth changing the belt given the car is eight years old.