First I would check and make sure that there is nothing physically wrong with the engine cooling system itself.
Unfortunately, since I'm not a mechanic, I really wouldn't know what to check other than the radiator, coolant level, coolant mix ratio, and make sure that your thermostat isn't sticking...
If you're sure that it's not a mechanical failure, it may very well just be the oppressive heat in your area. (I thought 103 down here in Dallas was bad)
If that's the case, you might want to look for an after-market radiator and/or electric fan....
Just my opinion...
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1998 Mustang GT
13.97@103
"Traction Impaired" or "Nitto Needy"
Pilot Proverb:
If all you can see out of the window is ground that's going round and round and all you can hear is commotion coming from the passenger compartment, things are not at all as they should be.