I never tried it myself, but carb cleaner can be used to locate a leak. Spray the cleaner at the suspected leaking area with the engine running. If your idle smooths out, then you found the source of unmetered air coming into the engine.

The carb cleaner is combustible and helps enrichen any air drawn in. Without the enrichment, the engine sees a lean mixture if a leak is present downstream of the carb. Please note that the other folks responding to your post are much more capable mechanics than I. It would be wise to carefully review their suggestions if the leak test does not pinpoint your problem.

Hope this helps,

Joe M