When I start to go the car goes but if I punch it or just put the pedal down a ways it starts to sputterish. When in park and push the pedal down, even slowly, it sounds like the engine is up, down, up, down consistantly.

I am thinking your problems are one in the same you have a safety lock on your shifter that will not allow you to shift it from park unless you push down on the brake which then send a voltage signal to unlock your shifter but if the voltage is never sent you will not be able to shift it out of park. There is an emergency access through a small hole next to your shifter that you could put a screw driver in there and push down to unlock your shifter. Sometimes this hole has a small cover over that you need to remove. Check to see if your brake lights are working if not this could be the problem as the voltage needed to unlock your shifter usually comes from the brake switch down on the brake pedal let me know how it goes.

What's wrong? Will the Parking brake engage? Or is it not working at all?

Try jacking up car and put on stands as high as poss as you could have air returning when the pedal is returned ,so jack up car pump pedal 4 times fast and hold down bleed l/h/s/first ,do 2 times then the r/h/side and then push down pedal clamp rubber flex hose over back axlewith small G clamp if pedal good do same to FRONT

If you're not losing any brake fluid then it sounds to me as though the master cylinder is bleeding fluid between to two chambers allowing fluid to pass from one to the other which would decrease the pressure on one of the lines leading to the proportioning valve, thus setting off the 'brake' light.

Orrrrr,

IF it does NOT have the hydroboost system the following steps MAY help diagnose if it's a booster problem.

(Copied and pasted from a youtube comment)

Test 1) 1. Start the car 2. Let it idle for 2 minutes 3. After 2 minutes turn off the car 4. Pump the brake pedal 3 times 5. The pedal should rise every time if it does then the Booster and Check valve are OK 6. If the pedal doesn't then the is an issue with the either one, run tests 1 and 2.

Test 2) 1. Start the car 2. Let it idle for 2 Minutes 3. After 2 minutes push down the brake pedal and HOLD it 4. While holding the pedal down turn off the car 5. The pedal should NOT rise for at least 30 seconds 6. If it doesn't rise then the Check Valve is good 7. If the pedal rises before 30 seconds then the Check Valve is faulty.

Test 3) 1. Shut off the Engine 2. Pump the brake pedal 4 times 3. On the 4th one keep it pushed down and start the car while holding the pedal down 4. The pedal should sink down. 5. If it sinks, the booster is Fine.

Myself, I'm leaning towards the master cylinder having an internal 'leak' or bypass problem.

Hope this helps.

Is it a "stick" in the console between the driver and passenger seats, or is it a pedal you push down? If it is in the center console, try starting the car, putting it from park into NEUTRAL with your foot on the brake, and pull up on the stick a little while pushing in the button. If the button goes in, push the handle back down, put the car back into park, and take your foot off the brake. I'm not real familiar with the Pacifica, so a description of the parking brake would help.

detemp ball/button could be broke check the brake linkage/switch to the trans if not any of those block the tires start it and have someone get in and hold the brake then get under it and see if you can move the linkage.

There's a plunger switch on the brake pedal arm up above the pedal. It probably isn't working now. There will be a way to move it as an adjustment, which you can try to see if you can realign it. If that doesn't work you can replace it, or just jumper the two wires on the switch itself to effectively permanently close it. Then the interlock will be disabled and you won't have to push the pedal down to take the car out of Park.

newer vehicles require you to push the brake pedal down to shift from park, maybe the switch went out.

Chances are you're parked on a hill. You need someone to push on the car to take the pressure off the parking pin in the transmission. The other possible problem is there is a solenoid the won't release the gear shifter until the brake pedal is depressed. If you are pushing the brake pedal before trying the gear shift there is a malfunction in this system. This is not as easy to fix. If you aren't mechanically inclined I recomend taking that to a mechanic. If you are so inclined let me know and I can help guide you thru the steps.

its sounds like the classic case of the stop lamp switch going bad,you step on the pedal,esp sees a difference in the pressures at the booster,but doesnt actually see the pedal moving because the switch has gone bad,also causing the vehicle to not come out of park because this vehicle is designed to not come out of park unless the key is in position 2 and the brake pedal is depressed.if you really need to get the car out of park to get somewhere,on these models i believe there is a flap of plastic just below the d on the shifter panel that has a spring on it,just put a thin screwdriver(i.e.-pocket screwdriver) and least 4 inches long,press it straight down and pull it out of park-with your foot on the brake pedal of course)get this fixed asap-drop the panel under the dash,under the steering wheel-on the brake pedal assembly,theres a part where the switch goes,get the part before you start the job and youll recognize it right away,depress the tab and turn it clockwise to remove it,on the new switch,pull the detent switch all the way out before installation,put some type of bar between the seat and the brake pedal with vehicle on and adjust the seat to press the pedal down and keep it down,install the switch and release the pedal slowly to push the detent switch back it,once its all the way down,grab the pedal by hand and slightly pull it towards you,it should click one more time,now its adjusted,put the panel back on and your golden,just saved about $200 bucks in diag. and install labor-good luck bud
jess