Toyota Repair: Engine noise, power steering pump, drive belts

Question
I have a 99 Tacoma Reg Cab 4x4 with a 2.7l 4cyl and a 5 speed. It has 128,000 miles on it.
Lately I have noticed that after it warms up and idles down I hear what soulnds almost like a slapping noise.
I have tried to isolate and it almost sounds like it is coming from the AC compressor.
If I shut off AC it really doesn't seems to get rid of the noise.
If I rev up the motor it goes away.
At first I thought it might be sheet metal coming loose but I am afraid I won't be so lucky.


Answer
Check all the drive belts for wear, they can cause noises.
Disconnect the belts one at a time and see which one makes the noise go away, this way you can eliminate things like the power steering pump, A/C compressor and water pump.
If the noise is still there with all the belts disconnected the noise is an internal engine noise, in that case you should have a toyota dealer diagnose it.