1. Burp the system again.
2. Make sure cooling fan is working: Disconnect fan connector, battery positive to 1 terminal of the connector, ground to the other.
3. Check the fan relay (in the under-hood fuse/relay box)
4. Jump the fan switch to see if that's bad
If all those are good:
1. Check for exhaust gases in the coolant
2. Check for milky oil
3. Check for water in the cylinders
If all those are good I would suspect a bad water pump. Which means it's time to change the timing belt also.
If all else fails, download the service manual and it will take you thru diagnosis step-by-step: Looking for a 7th gen manual for free? (UPDATED!!!)