I am working on a friends Freestar and it is giving me fits! It all started this summer when it wouldn't accelerate over 20 mph. I ran the diagnostic tester on it and I got the P0340 code. I changed the CPS and the fuel filter after the first time. It seemed to fix the problem for a few weeks. Then it happened again.....same code popped. I had bought a sensor that had a limited lifetime warranty so I got the sensor replaced for free. That fixed it for a month or two and then......you guessed it.....its back.
I noticed the first time that the van hit rev limit at roughly 4K RPM. I didn't pay it much mind but now that it has reoccurred I wonder if this is tied into the issue as well.
Any help that I can get would be greatly appreciated as I am close to screaming at this van!!! Thank you!!!

 

There are quite a few problems that will cause a PO340 code and not even be related to the cam system. Wondering if in the process of replacing the sensor you are shifting the wiring around some and by George it works. Then the wires get to their original location and the problem returns. One of the things that will cause that code to come up is the alternator/ and or the wires coming to it. One of the things you can try is unplug the plug on the alt and see if the problem is still present . If it is gone it could be the location of those wires or the alternator itself.