X2 on this! This is my go to method for tracking down vacuum leaks that aren't evaporative emission component related. With engine running, spray along vacuum lines, elbows and fittings. When the engine RPM goes up, you have found your leak as the combustible starting fluid is being added to intake.

 

X3 on brake cleaner, use the straw so you can be accurate and isolate the leak, mine was the injector O-rings as well.