Might try a new fan clutch if it's not the waterpump. Cause if you go with something like an electric fan you'd just be putting a band-aide on it and not fixing the real problem.

 

I'm not using an electric fan, I hate them. The last mustang I had overheated with one (88 GT)

 

What about the lower radiator hose? Are you sucking it flat. When you turn high RPM's like on the highway you could be restricting the water flow just like a clog in the radiator would. I had a similar problem. I was overheating during acceleration and cruising at speed. Mine was bad enough that I started blowing gaskets on the water pump. This happens especially with older hoses. Squeeze it and if it feels really soft (especially cold) it could be a quick cheap fix. Only a possibility.

 

another thing to check for is your gauge working properly, you're temp sensor as well, and that you don't have any air in your cooling system. If those check out good, then look for a bad thermostate, waterpump, radiator, fan clutch, and ignition timing, and fan shroud. Thats all I can think of for now. GOdd luck.

 

Fan clutch was bad

 

Ha ha, I win. lol, glad you got it fixed.

 

indeed [sm=smiley20.gif]