Chevrolet Repair: 1996 Chevy Tahoe Pinging Noise Question, chevy tahoe, vacuum leak

Question
I own a 1996 Tahoe with 140k miles on it. Other then a recent intake manifold incident it runs great. Lately and before the problem I have been hearing a loud pinging noise primarily when I accelerate after when the truck is cold and after breaking once its warm. I have found somewhere else on the net a reference to this type of noise being Exhaust related which after thinking about it would be consistent (its loudest when more exhaust heat is generated when accelerating and makes the noise when slowing down when it cools a bit) I am set to believe this explanation but I would still like another opinion on other causes of the noise because of age of the truck and the miles it has. At first I was thinking transmission of IFS but both work fine or at least as designed. Any help would be appreciated

Answer
Hi Joel,
Sounds like a vacuum leak.
You sure the intake manifold is sealed?
Other possibilities are the EGR valve sticking, and the vacuum hoses.

Here is another thought.
You say it pings after braking....the brake booster uses vacuum, and if it is leaking, that is the same as any other vacuum leak. See if you can hear it leaking vacuum down under the dash.
You might even hear the engine RPM's change while sitting and applying the brakes.

Van