You need to inspect all rubber hoses to include the air inlet hose prior to the intake manifold, you have the right idea but even a repair shop will need to do a visual inspection, its common that they get old, dry and crack, get rub marks to the point of leaking air and burnt from hot exhaust, etc.
You can spray carb cleaner around to find a leak, some mechanics spray some water around to find a leak but don’t go overboard. All knowing that your problem may not be an air leak but this is the best step to start inspecting if you don’t have a scan tool.