Wow, what a difference!
My coolant temp. was running 210-220 on the gauge. while changing the thermostat(to a 180) I noticed that my coolant was BROWN and nasty. I removed the thermostat housing and the lower radiator hose, turned on my water hose and let er run. I also flushed out the radiator and while I was at it I removed and washed out the overflow jug. After filling it back up with new antifreeze ,my temp stayed at about 190 on the gauge. The car seems ALOT more peppy and now I'm not hearing the clatter at WOT. I also changed my trans filter and installed my trans cooler. Might check your cooling system!