RPM Surging

I have a 91 honda civic dx. Just recently the motor is surging really badly at idle and the idle has moved to a high idle RPM. I replaced my PCV 3 months ago and if I clamp the hose to it to restrict the flow the surging stops, but nothing appears wrong with the valve. I suspected a vaccuum leak but I dont know how to find it, I cant hear it. Thanks for your help!

get a can of that air propelled duster cleaner stuff. its really cold so it will freze the hole in the line for a few seconds.

Do you mean the brake clean spray or do you mean the computer parts spray? Thanks for your help.

you can use brake cleaner. spray it around the engine, if you spray over a vacuum leak, you idle will rise and youve found it.