Need some help

About 2 weeks ago I was driving my 2002 A4 to the store it was raining out and my car felt like it slide a little and then the EPC light came on. I was able to get it home since I was still close but it had little power and the RPM's went up and down. Next day I had to fly out of state for 2 weeks for work during this time my wife started it and she found the floor mat was up under the gas pedal she moved it and the light came off and she was able to drive it with no issues (She was with me that night when it came on). She started it a few days later and it was hard to start and the light came back on and the RPM's bounced up and down. I just got back yesterday and started it a little while ago and it was hard to start and once it started the rpm went up high and came back down and started to bounce around again hovering between 500 - 1000 rpm, but no EPC light. Now I know it needs a cam shaft position sensor because its throwing a code for that. My question is did the cam shaft sensor go and needs replaced or could there be another issue.