"Jumping" sink

I have a quick question.
To start, I am not very versed in plumbing. I have just bought a house (1975) which has all copper pipes. I have soldered on new washer/dryer valves (with extensions), as well as replaced the main seal and drain valve that comes right off the main.

The kitchen sink (not aware of brand...I am at the apartment right now) is a chrome fixture, two handled. It is the only fixture I am aware of that does this. When the water is turned on it "jumps" rythmically (about once every second). It does it with both the hot and cold water. What causes this and how do I stop it? It seems to lessen and almost go away when I turn both hot and cold full blast.

I don't believe it's air in the lines as I have now went to every water outlet and used it.

The only thing I can think it might be is some gunk/etc in the aerator (haven't had time to check...the whole family came up for easter and helped get beds set up). What else should I check?

Thanks,
-Matt

Could be a loose washer or a loose stem in the cartridges

It sounds like its the diverter for the side sprayer activating. Check the sprayer hose and sprayer to make sure they are not leaking. If they are not leaking the diverter will probably require replacement. Post back with the make/model or, a picture is that is needed for more information on how to change the diverter.

jump

The diverter is the most likely culprit, along with a leaking spray head that makes the diverter "clunk" to refill the line periodically.