I have a 94 4wd p/u w/ the 22re. my engine runs great, except for when it is idling and i depress the brake peddle. the engine then idles really weird, kind of a strong then weak then strong then weak, so on and so forth. it never cuts out, though, and continues to idle normally when i take my foot off of the brake. i've only noticed this after driving, like at a stoplight. thanks jason
the power assist unit is suspect, causing a vacuum leak.
Check for a vacuum leak in the brake system hoses. When brakes are depressed the electronics sends a signal to the ECU to cut speed of engine.
Assuming no vacuum leaks as mentioned above, its likely because your idle speed is set too high.
I can exactly duplicate this "problem" in my '85 by bumping up the idle speed to a bit over 1000 RPM and it'll act up as described. Turn the idle speed back to normal, and it works fine. Its really not a problem, its supposed to work this way and if everything is set properly, you won't have the "problem".
Why is this the case? Because the ECU has logic built in that says if you hit the brakes and the engine is turning over 1000-1100 RPM, it'll cut the fuel to the injectors in an attempt to help you stop faster (no sense pumping gas into the engine when you are braking to a stop). So idle rises, fuel is cut, idle falls, fuel restored, idle rises, etc. Turn the idle back to 850-900 RPM where its supposed to be and it'll get back to normal. Idle speed is adjusted with the large slotted screw atop the throttle body. Turn it in to lower the amount of air passing through the throttle body at idle (and thus lower the idle speed).
If you don't want to do that or it doesn't fix the problem, here's a more drastic fix:
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