You don't clean it. Do you have a Helm manual? There is a test procedure. You need to test the harness connected to it to make sure that you are getting 5V between the outer two wires when the car is on.
Then you need to back-probe the connector so you can test it while it's plugged in and see that the middle wire is outputting the right voltages. To do this, try to get something (i used a bent cotter pin) into the back of the connector through the rubber that keeps the wire insulated. If you can get contact, get your multimeter and put the positive lead on the middle wire and the negative on the negative terminal of your battery. Now, with the ignition in the on position (car should not be running) at closed throttle it should output .5V and at WOT it should be close to 4V.
Honda recommends that you replace the TPS with the throttle body. I think that's a bit excessive and you can get a new TPS, but then you have to calibrate it. This is done just like you would adjust your timing by rotating the distributor, except instead of looking for correct timing with a timing light, you would be looking for the correct voltage output.