Just a random idea. You could check the condition of your radiator. We once had a crown vic that had a radiator clogged with dirt and dust that couldn't provide enough cooling.

Also, I heard there are coolant system cleaners you can use to clear out gunk in your system. I suppose you could have some blockage that won't budge with just a system flush with a hose. Could be worth a shot.

Also, why are you running a 180*? I've read on here numerous times that doesn't help anything unless you have mods and a tune to account for that.