major cooling problems in 1988 supra

after spending $600 dollars on a brand new radiator i thought my cooling problem was over but 5 minutes after picking the car up it began to overheat again when boosting. i then replaced the the rusty old thermostate with a new high flow one. this cooled it down a lot but it still overheats. what else could it be?? im running out of solutions and money

it could be possible that your cooling system is airlocked