Just for giggles…
have you checked the intake boot for any signs of splitting or cracks.
Also that the clamps are tight.
One thing you might try is using a propane torch (without the flame)
With the engine running and monitoring the fuel trims go around the engine where any possible leak can occur with the propane.
If done correctly and there is a vacuum leak on the intake side of the engine the propane will introduce more fuel into the engine thus lowering your fuel trims while your watching.
A good test but not 100% accurate.
Another is to spray water around the intake area and listen for the engine to stumble.