I have a 96 Eldorado that goes into limp mode around 190 degrees. I pulled the codes and along with the overheat code it also has a #8 cylinder misfire and a bad O2 sensor. Would a misfire cause the early overheat condition? Obviously the engine isn't actually overheating since there is no spillage from the surge tank and the temperature is too low. Could it be the temp sensor or possibly a bad pcm?