This kind of stalling problem often means the engine is not getting enough fuel and/or too much air. A cold engine needs a fairly rich fuel mixture to start, and to idle smoothly while it warms up. Rpm needle should not fluctuate at idle and that means you have a vacuum leak.
When you brake, the throttle is close, only the idle valve is open same as when you first start the car and the rpm needle jerks.
Check for loose or broken vacuum hoses, leaks around the intake manifold gasket or throttle body.
Check around the PCV valve, EGR valve and the IAC valve.
Check the battery for low voltage. It can adversely affect the operation of the ignition system and fuel injectors, causing stalling and misfiring. A good charging system should produce about 13.5 to 14.5 volts at idle.
Monday, January 11th, 2010 AT 9:56 AM