Chevrolet Repair: engine stumbling, vacuum gauge, chevy suburban

Question
i have a 95 chevy suburban lt 4x4 with tbi and it stumbles alot at an idle and tends to smooth out in the higher rpms.  it has a new exhaust,02 sensor, fuel pump, plugs, cap, rotor, wires, and i had it hooked up to a computer and it said all the cylinders were firing and there was no problems.  the service engine soon light is off and on and it tends to kick on more when im at a light idling for a minute or more .  the car starts to stumble alot and the service engine soon light will kick on.  what else should i check.  

Answer
Hello Herman,
If it stumbles worse when you are sitting with your foot on the brake, you may have a leaking brake booster, leaking vacuum.
Connect a vacuum gauge, and see, or disconnect the vacuum hose to the booster and plug it, just to see if it runs better.

Van