car intermittant overheating. took compression test. nothing under 90 PSI

Under what circumstances does it overheat. Idle, highway driving, stop and go? Has the coolant been changed in 13 years? Is there coolant in the plastic bottle? Is there a leak from the thermostat housing (made of plastic) located in the front of engine near the intake manifold? Did you ever add just water to the radiator? That's a no-no. Try flushing out the system and filling it with new 50/50 mix.