sensor issue on 2002 cougar v6.
 

I have 2002 Cougar v6 automatic with 66,000 mileage. and transmisson act crazy when it change gear and acceleration. I took to shop and computer said it need "Transmission Range Sensor", it won't pass 3000 rpm. I called part stores and they said "I never heard that" so what other name to called transmission range sensor? How much I can get it and where that part local underhood? Part stores also said input or output too. Please i need transmission work right. Thank you so much for helping to giving me answer.