Spray carb cleaner around where the carb and intake manifold mount to the engine. If it smooths out you found your vacuum leak.
Don't over those new parts you put on. All you need is a gentle snug. You might of warped something causing vacuum leaks.
NO impact guns are needed. Leave those for blade removals.
slomo
NEver liked the idea of trying to find an induction leak with a flammiable gas / liquid.
Too much of a chance of it igniting while your nose is in there looking closely at what you are doing.
The USA is the only place on the planet whee mechanics get taught to use propane to check for manifold leaks.
Usually for safety reason I would use WD 40 or similar from trigger pack ( because spray can propellants also burn ) as you can see exactly where it is going and if sucked in generates a lot of white smoke but no engine damage.