Good point, that would be something else to check.

remains in position.

do you have any idea where it is?

The pedal should not go down no matter what, weather the booster is good or bad, the pedal should only go down if there is a hydraulic leak or a internal problem with the master cylinder. With no power booster the pedal should actually get rock hard. If the power booster had a leak it would be a vacuum leak to the engine, could set a code and or cause rough running, or even a stall if the leak was big enough. Fairly rare though.

So when did it start stalling? Was it after maybe an oil change? If the egr gets stuck it could cause a stall, or the throttle body could be dirty and the butterfly is completely closed of causing excessive fuel, then when you retry to start the engine will not start without cranking to clear excess fuel. If the engine runs fine other than the stalling, with no codes, try these simple checks take the egr value off make sure the pintle is not stuck and the hole is not blocked with carbon, check the throttle body butterfly clean the opening. As for you being charged $1000 dollars and the problem is ongoing go get your money back, you paid to fix a problem not have the mechanic to try to fix the problem, sounds like they are like the lawyers that say they have a practice. I had garages for 30 years if i could not fix the problem shame on me, and i did not charge the customer.

05 impala stalling/dying, random misfire
 

Last year i bought my very first car i am 27 years old, at first she ran fine but shortly after 3 hour trips i started to notice a jolt at a certain speed like my engine has hiccuped. I then took her to get a diagnostics testing and reading was P0300, which was a list of problems. Me and my husband thought we got everything on the list from spark plug changes oil changes to oil, fuel, and air filter changes to fuel treatments thinking water was in my tank, buying new hose clamps, the problem unfortunately never stopped. My plan was to take it to a chevy dealer.

i was getting ready to be on my way for work and when i went to start my car it refused to even try to start, it didnt turn over or even make a sound to try to turn over, me and my husbands thoughts were that its a censor problem or the alternator. A neighbor of mine has a brother who is a mechanic as they gave me a ride to work their brother came and looked at my car, there was something i missed in changing the spark plugs and wires in my car, i didnt know that you have to change the Coil Pack everytime you change the spark plugs, if you dont it fries the Control Module. When my husband looked at the one we have in the car, it was a factory model and the car hasnt had a tune up from any of the previous owners. Today hubby is changing Coil Pack, Spark Plugs and Wires, the Control Module and we got a new battery since the one in the car was apparently too small for this car. I will post about changes hopefully we see improvement although i know this post is old. Someone like me looking for answers will find this post. Thanks SP