My car just recently started showing a hot temp. It does not go into the "danger zone" on the temp guage and it fluctuates while I am driving and sitting in traffic. It hovers between normal and about halfway to the "danger zone". Sometimes it will go up or down when I am driving. Sometimes it will go up or down when I am sitting in traffic. There doesn't seem to do one thing or the other consistently. I checked the coolant and it is full, however when I opened the hood after shutting the car off, I heard a "bubbling" sound. Like boiling water. Any ideas?

engine has 80k miles stock intercooler evo 16g big, down pipe, 550cc injectors

can you please help stock thermostat and radiator cap