although i was off in my description of how it works exactly, i stand by the fact that i believe your fan clutch is still the source of your overheating issues, it's easy enough to burp the system of air and change out the fan clutch, if only to troubleshoot and cover all of your bases
mine just spind very easily. and my old mans gt is kinda stiff to move around. i also have a flex a ligth fan i just dont know what size spacer it takes.
I wouldn't use the flex fan. I agree with 91 notch. Try a fan clutch. They are cheap, easy to change, and you can get them at autozone. When I changed mine, I didn't even take the belt off. Just let the pulley wedge in place from the tension.
I recommend buying a Ford OEM Fan Clutch - I have heard that the aftermarket ones are junk. I bought mine at RockAuto.com who has very reasonable prices.
I wouldn't use the flex fan. I agree with 91 notch. Try a fan clutch. They are cheap, easy to change, and you can get them at autozone. When I changed mine, I didn't even take the belt off. Just let the pulley wedge in place from the tension.
Flex fans have been known to come apart at high rpm. A friend of mine had this happen to his 93 GT. A blade broke off and took out his radiator and brand new glass hood.
Either upgrade to electric or pick up a replacement clutch.