2002 Ford Taurus Car will not run over 40 mph, but RPM's ar

Sounds like your car has gone into what is known as LIMP mode. You need to have the cars computer read to discover where the actual fault lies. Most good autoparts stores (autozone etc.) Will do this for free. Get back to us with the codes for more information. The PCM (computer) may be the actual fault i'm afraid

Hardware Limited Operation Strategy
HLOS is a system of alternate circuitry that provides minimal engine operation if the PCM or EEPROM fails. During HLOS, all self-test function will stop and system will be controlled by electronic hardware.
HLOS Allowable Output Functions:
Spark Output Controlled Directly By CKP Signal
Fixed Fuel Pulse Width Synchronized With CKP Signal
Fuel Pump Relay Energized
Idle Speed Control Output Signal Functional
HLOS Disabled Outputs To Default State:
EGR Solenoids
No Torque Converter Clutch Lock-Up