Engine surges occasionally when stopped at a.

Any codes?Have you tried cleaning the idle air control valve?Or looking for vacuum leaks?

You can't look for vacuum leaks with soapy water because vacuum is the absence of pressure and wont blow bubbles. The way I check for leaks is with some carb spray spraying it around at idle and watch for a rise in or fall in rpms stumbling or dying.

There are so many things that could cause a surge. If you have no codes and no vacum leaks I would have to suggest that you take it to a shop for diagnosis. You don't want to waste any money on uneeded parts. There are dozens of things that could cause your issue.

No I can not pull up vacum diagrams.