98 contour 2.0 zetec

Alright, I've got a 1998 Ford Contour with a 2.0 Zetec. My car gets all the way, almost into the red zone, and both fans cut on with full force, almost makes my car stall. I turn the air on only one fan comes on, thats good though. I had to replace the other fan motor, im guessing the lower speed one, and it only comes on when the other one comes on full blast. I have replaced the fan motor, coolant temp. sensor, and the thermostat. HELP ME, lol, But really, any feedback would be greatly taken.

do you have an auto trans?

manual