Had to convert a room to a HCP accessible full bath... about the same time the house developed this pulsating thumping on the cold water side... all faucets/ toilets when they use water, I get a pulsation that is about equal to .01 galllon frequency (I had a walkie talkie in the house and watched the water meter needle and found the sound is synched.
I do not get this with hot water usage.

I have had the inside pressure regulator replaced. I have had the outside pressure regulator at the pump replaced. I have had the pump replaced. I'm $500 poorer and still not enjoying the vibrations in the pipes.

Ideas?

Make sure all valves are wide open. One at a time, close them off and test for the condition. I suspect the new faucet or toilet. If you can not isolate the condition, you may need to install an expansion tank or water hammer device.

Making sure I understand... I open all the cold water valves in the house (and outside?) I expect that this will have the pipes numming pretty good. As I close them one at a time, if I find a guilty outlet the sound would stop? At that point, continue to close all off. Then what assuming I find a guilty outlet?

Do I start closing at the highest elevation, lowest or does it matter?

I'd agree. The new work is suspect. Either the shut off valves or what was replaced.

Another thing that will cause it is not securing the pipes.

Guy reccomends opening the SHUTOFF valves for the fixtures and the main. Not the valve that causes water to come out.

Start with the shutoff valves for the new work and close them.

You can use a binary technique to isolate the problem. Close half the valves. If the problem is present. Open them and close the other half.

Close half the half with the problem and do the same thing, rather than one at a time.