Do You Have Your Fans Set Up As Pushers Or Pullers,
I Had Clearance Problem So I Put My Electric Fan In Front Of The Radiator And It Pushes The Air Thru - I Have A Big Block With About 650 Hp, And It Never Goes Over 185 Degrees - Traffic, Burnouts, Or Racing... I Would Think You Have A Water Flow Issue, Try Taking You Radator Cap Off - Start The Car And Watch To See If When The Thermostat Opens If You See Fluid Flow.... Try Changinge The Fluid - I Know That Sounds To Easy But - If You Tried All You Said I Would At Least Put New Fluid In It...