Join Date: Jan 2015
Location: Northern Indiana
I would buy a $40-ish mechanical temperature gauge and temporary install it under the dash to find out what's going on. Since you seem to have covered all the other bases, what is the condition and stated temperature of the thermostat? Whenever I have something weird going on that is the first thing I change. The fact that it didn't puke is a good sign.
65 C Code hardtop from California still wearing it's original paint.
Roller 331, TW 170 heads, T-5z, FiTech EFI, FPA Headers, Arvinode exhaust, SoT Bilstien coilover front suspension, TJ on eBay 8" 3.40 Trac-Loc 3rd member. Mustang Steve 2008 GT bracketed 12.4" front disks