99 suburban brake/computer problem? HELP!

Ill log in when I remember my password. til then I have a problem I hope someone can offer msome advice on. I have a 99 Chevy Suburban with soft brakes that makes a ssssssshhhh air escaping noise which sounds like it comes from under the brake peddal. I have plenty of fluid, no apparent leaks and vacuum hose seems solid into the booster. One weird thing, when I apply the brake idling in park, the engine rpm increases slightly(100rpm) and seems to cut out (miss some)?

any ideas?

[moopups]

Power brake vacuum booster diaphram rupture.

[agmantoo]

I will second what Moopups said

Originally Posted by centexguy

Ill log in when I remember my password. til then I have a problem I hope someone can offer msome advice on. I have a 99 Chevy Suburban with soft brakes that makes a ssssssshhhh air escaping noise which sounds like it comes from under the brake peddal. I have plenty of fluid, no apparent leaks and vacuum hose seems solid into the booster. One weird thing, when I apply the brake idling in park, the engine rpm increases slightly(100rpm) and seems to cut out (miss some)?

any ideas?

me again, thanks for the responses. I was afraid that might be the problem. I changed one many years ago. As I recall it wasnt too fun or cheap. oh well, I guess Ill start on it tomorrow. thanks again.
btw how does applying to brake affect engine (the missing) ?

Originally Posted by centexguy

me again, thanks for the responses. I was afraid that might be the problem. I changed one many years ago. As I recall it wasnt too fun or cheap. oh well, I guess Ill start on it tomorrow. thanks again.
btw how does applying to brake affect engine (the missing) ?

me again. the busted diaphram causes a vacuum leak, right?

[agmantoo]

Correct

[wtipc]

I'm having a similar problem with the brakes on a 96 Silverado Pickup, except that my brake pedal is hard. I get the sound of air escaping when I press the brake pedal and my engine runs bad/misfires now. No leaks, plenty of fluid in reservior. I've bled the brakes, but that didn't help much. Please help!

wtipc

[Hip_Shot_Hanna]

same problem only worse ,wtipc, and the same cure, that big pan like thing behind the master cylinder is busted, replacement is the only answer.

[wtipc]

Thanks, I appreciate your help.