2002 pt overheating, sometimes when I turn it off overflow bubbles

If the thermostat and punp are good, see if the fan runs especially with the air on. Could be the fan or one of two relays.

Let me tell you my story with my pt. I started to overheat in McDonalds Drive thru. Checked coolant it was the proper level but bubbling. let it cool down drove it around it was fine for a couple days. Decided to check the operation of the radiator fan (it worked). Overheated on the way to the store so I tested the antifreeze and it was positive for motor oil so I replaced the head gasket and sent the head to the machine shop. Head gasket problem solved. Two days later the radiator fan motor failed and the fan would not operate. I suggest you buy the fan online for around sixty bucks and have someone put it in cheap.

I'm sure this has already been repaired due to the date of the original question but just in case- there is probably some type of short in one of the 2 relays to your fan. Same thing happened to mine and I replaced the tthermostat, radiator cap and all the other little items until I had someone check the wiring. They found that there was a short of some type in the one wire that controls turning the fan on if the car is idling or running at a lower speed (the temperature is fine when I drive at 65 and faster :)). Just a suggestion to check for if this is also your issue.