I'm not sure about that. I always thought my '94 was running cool, so I changed the thermostat. The parts manual says the factory recommendation was something like 160. Still not sure, I checked the sending unit out and it's fine. Probably should have called the dealer, but figured it was better to be a little cool than too hot. It runs fine, and the heater worked well this winter (first winter with it). The rust issue seems valid though. Your best bet is to call a Jeep service department.
Turbocharged 4.0, 35" Kevlars, 33 spline Detroit D44, 4.88s, heavy foot.