Ej22

Anyone had any issues with air bubbles in their cooling systems? Replaced a heater hose and didn't bleed the system properly. Temperature started spiking a couple days later so I bled it twice with a home made coolant burping kit and had it checked by a subaru specialist. Everything was functioning correctly and a cooling system pressure test was performed, there were no leaks. No trouble for a few days and then randomly spiked again driving home normally after some boosting. No bubbles in the overflow. My engine is an Ej22 with v4 STI heads running 20psi.