More than likely the defective component here is your PT Cruiser's Ignition Coil. It's not a rare fault. The ignition coil provides spark to all 4 cylinders. Once defective, even for a single cylinder, the entire ignition coil pack needs to be replaced.
This repair can be performed at most automotive tune-up centers, however since you're in the process of getting your Chrysler PT Cruiser to pass the smog test we'd recommend visiting a smog check certified auto repair center. They can repair this fault plus ensure your PT Cruiser passes the smog inspection.
The smog center you visit will more than likely (should) conduct a thorough diagnosis first and ensure in fact that the ignition coil pack is defective.