I decided to replace my thermostat this weekend on my 89 FJ62 with 223k miles. I've got detailed service records going back to 1992. I've been running a high idle, about 950, so I decided to swap the thermostat since I have no record of it being done. I purchased all new sensors and the lower housing. I also needed to replace my AC idler pulley. It still squeals like a banshee after replacing the compressor, bearing, and new belts. I removed the fan shroud, fan, and clutch as well, taking the time to split the shroud correctly. The thermostat housing came out without too much of an issue. All bolts were intact. My big concern is the inside of the head. See the picture. Should I be concerned with all the rust? I had the coolant flushed and replaced at a local dealer less than 2000 miles ago with Toyota Red coolant. My temp gauge never showed hot, in fact, I thought the gauge always showed low temps. Should I re-flush? Is there a special sauce to flush it with other than distilled water? I searched the threads but couldn't find anything. Thanks in advance!