Cooling system

[Delorean17@xxxx]

Hello,
I can still not figure out why my fans are staying on at high speeds. 
After 10 minutes of driving they will rarely shut off. If they do it is when 
I am at a Stop Light but then they come right back on once start moving 
again. I reverse flushed the cooling system two times now and the results 
are the same. The car has 18k miles and the guy at the radiator shop said I 
must have an electrical problem and not mechanical. (please note, my AC Is 
NEVER on)
The fans don't come on very smooth. The fans are spinning the right way 
and were just rebuilt by john hervey. I have a light that tells me when the 
fans are on. The light flickers as the fan relay 
clicks(mini-brute,specialtauto.com) frantically when the fans switch on 
sometimes. I thought oh! The relay must be bad. I tried 2 other relays and 
they all flickered before the fans came on also so I ruled that out. I then 
removed the 40A circuit breaker and ran the system without it to see if that 
was doing the switching but that wasn't it. The circuit breaker doesn't even 
get warm so I think its fine. What could be causing this rapid switching? 
Could it be the otterstat? My temp gauge stays a needle width under the 2nd 
white line just where it should but the fans are on. I thought maybe my pump 
is going but when I replaced the water hoses under the manifold last month; 
the pump looked fine, no wobbly pulley, no leaking. Can a pump go bad 
without any signs?
For a test I disconnected the fans and let the engine get very hot, just 
past 220 and then turned the fans on and immediately The gauge went down to a 
normal temp. this little problem is driving me crazy. I have driven 2000 
miles so far with the fans on for about 1800 of them......The front radiator 
deflector is in place, new thermostat, auto bleeder, and all new hoses, new 
otterstat, fan fail jumper, bla bla bla it is real late, I hope this all 
makes sense.

Thanks, 
David
IN2TIME-MICHIGAN