My lincoln going up the highway regular speed then the trac light comes on and slows my speed down what is that problem

as with any other warning light on your dash......get the trouble codes read and then you'll have a starting point. Don't ask us to guess which of the more than 800 possible codes is stored in your computer.

Accelerate while on the "on ramp" until you reach the speed limit + posted on the highway... this way when you reach the highway you will be going the same speed(or close) as the other vehicles ..you can blend in easily.. and NOT cause an accident by going too slow!! On the way down the "on ramp".. start looking at the traffic coming on the highway to find an opening to ease into safely. Use your mirrors and BLINKER... (its easier to slow down a little than speed up)

Run a diagnostic check on the car. If these codes come up this is what they mean. C1233 No left wheel speed signal
C1234 No right front wheel speed signal

C1236 No LR wheel speed signal
check wiring and sensors

Try to scan should be obd code then fix it.

look for recalls my ford windstar had one the abs system

You have a vacuum leak check all hoses and dash pots for hissing noise inside the passenger compartment first and under the hood this is why the air changes from different positions

I would start with plug wires rubbing on something and created a short.and is not compleatly worn through. a cheep place to start. good luck with it.

MAKE SURE TIRES ARE ALL THE SAME SIZE FIRST OF ALL,NEXT MAY HAVE A SPEED SENSOR NOT OPERATING PROPERLY OR BENT OR MISSING EXCITER RING ON FRONT HUB OR REAR AXLE. EITHER WAY THERE IS AN ABS FAULT OR A DIFFERENCE IN WHEELSPEED ON ONE OF THE FOUR WHEELS CAUSING TRAC LIGHT TO ILLUM. VEHICLE THINKS YOU ARE LOSING TRACTION AND APPLYING ABS AND MISFIRING VEHICLE TO SLOW DOWN UNTIL TRACTION IS RECOVERED

need to check the wheel bearings - tire size if you have replaced the tires recently

Does the speedometer work? Sounds like the speed sensor in the differential.