If it got up to an indicated 115C, and there was no coolant loss then you don't need a new themostat, a new pressure cap, or a new whatever that will likely be suggested. And removing the thermostat to "fix" a cooling problem is just plain stupid, but bubbas do it all the time.

If it has a viscous fan clutch check that it tightens at about 100C. If the electrics engage high speed at 105C, then they and their control circuits and components are okay.

Check the temperature gage connector at the engine sensor and make sure it is clean and making good contact.

If the fans and temp sensor connection are okay get an IR gun and check the temperature of the thermostat housing and upper radiator hose and compare to the gage when it is reading high.

Chances are the "problem" is the temp sender unit, a connection in the circuit, or the gage itself.

In stop and go driving, it is normal for these engines to get to 100-105C. Running the A/C may actually make them run cooler since A/C system demand will energize the electric fans at low speed, which will slow the rate of temperature rise and maybe keep it lower unless it's over 100F outside.

Duke

P.S. To those of you who suggest swapping parts willy nilly without even a thought of diagnostics or discussion of how the cooling system works, you're better off spending your time gaining some system knowledge and learning diagnostics rather than posting "solutions".