I have recently had a hissing from the rubber boot at the brake pedal where it goes through the the fire wall. Part of the booster assembly.It is part of the Vacuum system and there is a hole in the rubber boot that goes around the cylinder. does anyone know what this part is called or how to fix it. I am trying to avoid a costly trip to the dealer.[:@] I have no problems with the brakes but if i mess with the boot and make the leak open up more the truck idle starts to surge but not stall.

 

If the booster is bleeding vacuum into the dash area (at the brake push rod), the fix is a booster replacement..

 

Thanks Hayapower.
So I have to replace the entire booster assembly for a $5.00 part? that figures!!

 

Can anyone direct me to a good supplier for the booster. I can't find any for the 2003 specifically.

 

I was having this same problem. The hissing sound has now transitioned to a squeal coming from the firewall at the brake pedal. Did you have to replace the entire booster to resolve your problem?