i have a Koyo, S14 A/C fan (constant), S14 SR Hacked up shroud and Clutch Fan and my car runs ~180 at 12 noon on an 90 degree day doing 75mph on the highway...~184 with the A/C on. This was both with a stock JDM bumper and without.

i had a similar issue to you last year, replaced both the thermo and cap and haven't had a problem since. I'm gonna go +1 on shitty fans