1990 Dodge Shadow ENGINE REVS UP TO 2200 R P M

HOW TO FIND AND FIX THE PROBLEM OF REVING UP. WHEN THE CAR WAS NEW DODGE FIXED THE PROBLEM WITH A NEW GAS POTIONER. BUT I HAVE HAD IT IN SEVERAL REPAIR SHOPS TO NO AVAIL EVEN A DODGE DEALER SHIP. THEY REPLACED THE COMP. WIRE HARNESS, TROTTLE POS, AND MANY MORE THINGS AND IT WAS WORSE. I HAD THEM REMOVE ALL THE NEW PARTS REPLACE THE OLD AND IT RAN BETTER I PAID THEM AND NO ONE CAN ANSWER WHAT THE PROBLEM IS.
IT STILL REVS UP, A GOOD KICK OF THE GAS PEDDLE MAKES IT IDLE DOWN, THIS IS BAD IN SLICK ROADS.


11/20/08
I checked all things and found that when it is in a high idle you unplug the cooling fan wire from the thermostat, it will idle down like it should, but then the check engine light will come on, pluging in the wire to the fan the check light stays on. Shuting the car off the light will go out, but then comes back on a short time later. After doing this a few time the light will stay off.
thank you Harold--- oleagleye

11/29/08
Im new to the copputer so bear with me.
YES I HAVE DONE EVERY THING TO THE CAR THAT YOU SAID.
I FOUND OUT IF YOU UNPLUG THE COOLING FAN WIRE FROM THE THERMOSTAT HOUSING IT WILL IDLE DOWN INSTANTLY, BUT THEN THE ENGINE LIGHT COMES ON, AND IF YOU PLUG IT BACK IN SHUT THE CAR OFF THE LIGHT WILL STAY OFF FOR ABOUT TEN MILES THEN KEEP COMMING ON AFTER SHUTTING DOWN THE ENGINE, AFTER ABOUT FOUR TIMES THE LIGHT WILL STAY OFF BUT THE ENGINE WILL REV UP AGAIN.
I CANT FIND THE FAN CONTROL PLUG IN IN ANY AUTO SHOPS OR ON THE INTERNET. THIS IS A PLUG THAT SCREW INTO THE THERMOSTAT HOUSING THAT YOU PLUG THE FAN WIRES INTO.
NOW THAT IS THE BEST INFO I CAN GIVE YOU AND THE DODGE DEALERS COULD NOT FIND THE PROBLEM. COULD IT BE THE THERMOSTAT FAN PLUG.
THANK YOU HAROLD