1997 Pontiac Grand Am Power and stalling problem

I had my alternator checked at autozone and it checks out to be good, I forgot to mention my battery was bad and was replaced, but did not fix my problem. What would be the next step I should take? Thank you for your help.

I am not too sure what the output voltage is while being load tested, I had one of the clerks at autozone test it for me and they said it tests fine. I will go back and have them check it again and I will let you know the output voltage. KIf it is not the alternator, then you are suggesting its a computer problem? I had some one recently told me it may be the motor mounts that could cause this problem as he had a similar problem, is that posible as well? The autozone rep, says I should start replacing sensors, but I do not want to replace them one by one till it's fixed and am not sure if that is accurate advice. I have notice the stalling and dieing problems happens in park when I depress the gas or brake. The car runs pretty smooth on the freeway, but as soon as I slow down to I believe first gear and almost stopping, between 0 to 1000 rpms is when I have the shuttering problem. After driving and I put the car in park, it will die everytime, but will easily turn back over. I hope this helps narrowing down my dilemma. Would oil pressure cause this fluxuation too, from a intake manifold gasket? I hope this is not too many questions. I appreciate your time.

Ok, I will give it a shot and clean them out and let you know what I find. Thank you.

Ok, I cleaned out the idle air control valve, the EGR and PCV valves and I still have the problem. How do you test the throttle position sensor and the MAP sensor? The EGR does not have a gasket and am unsure if that is an issue. Soon after I cleaned those 3 compnents I turned the Engine on and let it idle. It idles fine, with radio on, A/C on and I turned the wheels right then left and no problems. As soon as I press the break, the RPMS start to go down and the engine wants to shut of. Just what I notice thus far, Any other ideas why I figure out how to test the MAP and throttle Position sensor?

I had my alternator tested and it has 12 volts come out and tests good. I replaced the PVC and the adjoining hose due to crack in the hose. I still am have the same power problems, especially when I depress the brake. Any other ideas, I would apreciate it very much.

I believe I may have found the problem. It seems there is a vacuum leak in the the Power Brake Booster. I am waiting for the part and after I install it, I will let you guys know what happens. Thank you.

I installed the brake power booster and new gaskets for the EGR. My car runs like a champ again, thanks to the new brake power booster and through some help of some mechanics. Thank you guys.