Camshaft Position Sensor

I have a 2000 Taurus, it is acting like its out of gas but has full tank. We had it tested and the code P0340 came up and it was "Camshaft Position Sensor" - Circuit Malfunction. So we bought the part and changed it out and it didn't make a bit of a difference. The car loses rpm's really fast. We hold the accelerator down because it seems like its going to die and we hold it steady at about 5,000 rpms and the rpm's just fall and rise fall and rise, etc. I dont know a whole lot about this car and the sensor, but i dont think its the sensor that's bad. I f anyone has any idea feel free to comment i'm open for any suggestions or ideas as for what could be the problem. Desperate need of help.

Will it die in Overdrive?

Actually it doesn't die in overdrive. what had happened was we changed the camshaft position sensor last night and woke up this morning and testedit again and the same code came up we looked and thought as to what could be the problem. We started the car up it was still sputering and oding the same thing so a friend had was giving me advice and said check the vacuum hoses one more time you might have knocked one loose when you were working on it. So I followed all of them because it did seem like there was a loose vacuum hoe and sure enough there was one. SO we hooked it up and the car ran fine. So I am not 100% sure if that hose has been loose since last week when we changed the spark plugs or if it just happened last night, and i'm still not for sure if it was the sensor but we changed it anyways and never the less the car is fine now. But thanks for the help.

Not that this is any help but a plugged fuel filter will make it run/not run the same way.