Toyota Repair: Overheating 91 Camry, radiator shops, radiator cooling fans

Question
The fans are electric.  Additional information is that the engine seems to overheat only at highway speeds, and cools down when you slow down.

-------------------------
Followup To
Question -
My used '91 V-6 Camry overheats.  It gets very hot and then cools off.  I have had the thermostat replaced.  I was told the head gasket was blown, and I had that replaced, very expensive.  I've had the air conditioner checked and rebuilt.
I'm thinking it's a sensor or something simple, but my mechanics (3 different ones) have been unable to diagnose nor fix the problem.
Please help.
Answer -
Before I can help you I need to know if the radiator cooling fans are electrically operated or if they are hydraulic operated from the power steering pump, look at the radiator and see if there are hydraulic hoses connected to the fans, this is very important if I am going to make a diagnosis as to what may be causing this overheating condition.  

Answer
Thank you for the reply, the most common cause for this problem is that the radiator flow is restricted, it is probably partially clogged, the best advise I can give you is to either take the radiator to a radiator shop and have it repaired or just replace it, the OEM radiators are very expensive and you can get an aftermarket unit from most radiator shops at around $250.