overheating

no i have not had my radiator check that was my next step i am waiting for a check before i can have that done. i had all my work done by my machanic and i know that they purged the air out in an earlier step of the problem, but im not sure if they did it after replacing the thermostat i would assumed they did but i will have to call them to see.

ive had all my work done by my machanic. they bled the system first then then put new thermostat in after that didnt work. I was thinking radiator could be restricted and its not letting propper amount of air in thats why it only does it while im going 55+. do you think that would be the next step to follow ?