So today my 2003 C240 became sluggish. I had just filled up my tank, and as i pressed the accelarator, my car would go about 1mph. I turned it off, turned it back on, and the check engine light came on--but the car drove ok then. I took it by an Advance Auto Parts and they ran the computer checker thingy. They got a code of P0121 which means it's the Throttle Position Sensor.
My question is:

How expensive is this sensor? How difficult would it be to replace myself? If difficult, how much will it be to replace?

Any suggestions/help would be GREATLY appreciated!!!


THANKS!!!