Mine had an overheating issue as well. It was really bad, and it got a little better when I cleaned the MAF. It was dirty causing the computer to run the motor lean. It didn't go completely away until I did the fan clutch. Agree with previous poster, the sound tells the tale. The new one makes a much louder rush sound. My brother checked my clutch by rubbing his hand on the fan blades with a hot motor running, and the fan stopped. It shouldn't have stopped if the clutch was doing its job.
Note, I do not recommend trying that... He is a professional mechanic so I guess he knew what he was doing. I don't get my hands anywhere near it when running.