Large vacuum leak that I can not find?

That sounds like a brake booster problem. The brake booster runs on engine vacuum to help make the brake pedal easier to push and easier to stop the tahoe. When a booster develops an internal leak, you can hear the vacuum escaping through the leak when you step on the brake. The engine stalls because the vacuum leak in the brake booster also causes a large vacuum leak for the engine.

To verify that this is actually the problem, go outside the vehicle with the hood open. Find the large brake fluid reservoir attached to a large round metal black (usually) canister on the driver's side of the firewall. (back of the engine compartment.) There is a large black rubber hose pushed into the top of the black canister, which is the vacuum line attached to the brake booster. Pull the rubber hose out of the grommet on the booster and stick your finger over the hose. Have someone start the tahoe. You will feel a considerable amount of vacuum pulling at your finger, and if you take your finger off the hose, the engine will stall. Also have someone step on the brakes while your finger is over the vacuum hose. If the noise is gone then you know the problem is in the brake booster.
Don't forget to re-attach the vacuum line to the brake booster. Failure to do this will result in the engine running very rough (if at all) and the brakes will require excessive effort to try to stop the tahoe.

a whistling noise will be a vacuum leak from some point. The Escapes are known for having vacuum issues in the rear of the engine due heat caused from the motor. The lines dry and crack out.

Usually the brake booster unit has failed or there is a rather large vacuum leak when these symptoms appear. Engine speed increases do to lean mixture (vacuum leak) and poor braking performance (brake booster does not have enough vacuum to function properly).

no think about this for a min. noise coming from eng. large oil leak, eng. dies. do yourself a favor Breeze it back to the dealer. you might have blown you motor

A vacuum leak. Look & listen for hissing noise where rubber or nylon lines come through firewall under dash near brake pedal. Also look under hood at large hose going to back of brake master cylinder, power brake booster.

the noise you can hear may be coming from the brake system booster.. This is a vacuum system and the hissing noise may be from a leak into the vacuum chamber in the booster. My advice is to take the vehicle into a reputable mechanic and have it checked professionally..

sounds like a possible problem with the power brake booster, its vacuum operated when you step on the brake pedal, it uses a large amount of eng vacuum, i would check the booster or the vacuum line and one way check valve in the line itself.

I would Look For A Vacuum Leak, Given the Fact that ALL that Work was Done in a SHORT Amount of Time, And The Brakes ARE VACUUM ASSISTED, that when Brakes are applied the ENG. Light Comes on, Seems to Me It all May be related. It does not take Much to Pop A Vacuum line OFF Accidentally

this noise is a vacuum leak at the power brake vacuum booster due to a tear in the booster vacuum diaphragm, u should have this replaced ASAP, it the leak gets worse the brakes will become very hard to push and will limit your ability to make a safe and timely stop.

If all maintenance is up to date.Check for vacuum leaks.If the vehicle has a vacuum leak.It will stall more often when the brakes are applied ,but could idle without stalling in park.Because of the vacuum demand for the brake booster,when brakes applied.Also do diagnostics on the computer for code status.Good Luck!!!