Alright guys... My mustang is running way too hot!! I know it could be a number of things... But I'm not sure where to start with trying to fix the problem? Thermostats? Have my cooling system flushed and cleaned? I'm just not sure where to start, and would appreciate any suggestions. Thanks guys!
-Paul

Thermostat first, they are notorious for sticking closed. While you are replacing it, (with no less than 180 degree), change the coolant. That should do it, unless you have a water pump problem which would be indicated by a leak out of the vent on the pump.

i have had a few already stick open, if it is still running but real hot it might even be that

[Cheesy E]

Wait till it gets hot and squeese the upper hose and see if its flowing it should be hard to squeese and youll feel water flowing strong. If not just hope its not a head gasket or crack somewhere.

[fvpnt0pony92]

its most likely the thermostat