Braking and loss of RPM?

[vVSmileyVv]

I've noticed that since I got my car idling correctly, I see a loss of rpms when I push the brake. This is to the point of stalling if I pump the brakes, and if it's cold and the car hasn't warmed, even stopping can stall the car. Wondering if anyone has an idea why this is? Brake booster gone bad? I can't find anything through my searches, and any help would be great.

88 dx 2.0 carbed.

[POS carb]

yeah, I'm thinking leaking booster or your car is just running very lean for another reason and using the brakes just pushes it over the edge. Plug the booster line and check idle. You can hear some boosters hiss when they blow

[vVSmileyVv]

Car doesn't seem lean, idles fine, accelerates great. The booster is rusted a bit. No loss of brake pressure though, wouldn't I see that if there were a leak?

[masster]

Loss of RPM when brake pedal pumping means vacuum destroyed because of unwanted air at atmospheric pressure entering intake manifold.

This can happen for 3 reasons:
1) a bad brake booster 1-way valve
2) a bad rubber hose between brake booster and intake manifold
3) a punched rubber diaphragm inside brake booster

Check 1) and 2) first. If they are OK, you have to replace the brake booster.

Note: a loud hiss when brake pedal is depressed is not always a faulty booster. It can happen due to booster air intake foam filter/silencer missing, dirty or split.

Hope this helps