Lately my car has been having a few heat issues when driving, normally it used to sit just above the 1/3 way mark, lately its been hitting half way and jumping to the last mark on the guage before the overheating mark. Replaced the thermostat today and it still did the same thing going up the highway, the guage is all over the place, anyone had temperature troubles with a 4K-C before? any suggestions as to what it might be? had the engine apart 6 months ago and the head gasket was changed then, only other thing I can think of is to try torque the head down a bit more... (suspect it has been chewing some water lately so i'm going to have to keep my eye on it)