The Nissan Path

My car’s RPMs consistently drop whether I’m idling or driving. So far I’ve replaced the spark plugs, knock sensor, crankshaft sensor, fuel pump, and cleaned the distributor (should I go ahead and replace the assembly?) I also cleaned the MAF sensor and ran some Techron through the system. Nothing has helped and the RPMs are only getting rougher.
I noticed while examining the engine today that a part labeled ati75-7 was ticking. What is this part and is it supposed to be doing this? Any ideas as to what my problem is/are? Any help is greatly appreciated.

"ati75-7" is not a Nissan part number. It would be a lot easier for us to identify the part if you could provide a picture of it. You can use an image hosting service like Photobucket to do it or make a short video and upload it to YouTube if that's easier for you.

A bad or failing distributor might cause these problems, but it is impossible to say from a forum level. Signs would include oil or metal shavings found inside the distributor housing, excessive play in the shaft, binding in the shaft (distributor would have to be removed to test this) or perhaps evidence in the way of broken or erratic spark patterns when using an oscilloscope to check the ignition system. With the number of bad distributors that seem to be popping up lately, it's definitely something to consider. If you replace it, it's best to stick with genuine Nissan.

You might want to test the idle air control valve to make sure that is working properly. Also, make sure the base idle and ignition timing are correctly set per the service manual procedure. An intermittent failing fuel injection is possible and some VG33 engines due experience leaking intake manifold gaskets, although it's not a real common problem.

Neither the knock sensor nor the crank position sensor would cause these symptoms. The crank sensor on VG engines is only used for ECM monitoring and doesn't affect engine management.

It ended up being the distributor cap & rotor. Was worn down pretty bad. After replacing it the car is running great.