I drive a cadillac deville 95' When I crank my car and apply brake to shift into gear my gas pedal pumps (moves really fast up and down). Then after I take off my car smell like its burning and its also jerking ( taking off really really fast I almost cant hold it) its like I have my foot on the gas and brake together because it will speed up really fast and then just jerked into a slow curse some one help me please Thanks

Could be the interlock brake switch . don't guess an just replace parts . You don't know how to test , take it to someone who can .

Something wrong with the shift lock system maybe. Safety system that won't allow the gear selector to move from park unless the driver is pushing the brake pedal . Do your brake light's work ? Does your caddy have floor or column shift ?
Automatic Transmission Shift Lock Control Description and Operation (Floor Shift)
The automatic transmission shift lock control system is a safety device that prevents an inadvertent shift out of PARK when the engine is running. The driver must press the brake pedal before moving the shift lever out of the PARK position. The system consists of the following components:
• The automatic transmission shift lock solenoid (serviced as the automatic transmission shift lock actuator), as well as the body control module (BCM) and the engine control module (ECM).The shift lock solenoid is located within the floor shift control assembly with vehicles equipped with floor shift.
• The BCM controls the voltage supply circuit of the shift lock control solenoid. The following conditions must be before the BCM will supply voltage to the shift lock control solenoid.
The BCM controls the voltage to the shift lock control solenoid through the shift lock control solenoid controlled voltage circuit. The following conditions must be met before the BCM will supply voltage to the shift lock solenoid:
• The ignition is in the ON position.
• The ECM sends an input via GMLAN serial data to the BCM indicating the transmission is in the PARK position.
• The BCM determines the brake pedal is applied according the brake pedal position.
Since the shift lock control solenoid is permanently grounded, the BCM supplies voltage to the automatic transmission shift lock control solenoid, mechanically unlocking the shift lever allowing the driver to move the shift lever out of the PARK position as the solenoid energizes. When the brake pedal is not applied, the BCM turns the control voltage output of the shift lock control solenoid OFF, de-energizing the shift lock control solenoid. The de-energized solenoid mechanically locks the shift lever in the PARK position.
During remote start operation, the BCM will de-energize the shift lock control circuit, locking the shift lever in the PARK position.

Just turn the car on, but Dont start it and put it in nutruel then start it... This she work til you can afford to fix it...

Does the shift lever move at all? Are you stepping on the brake pedal when you try to shift out of Park? Do your brake lights illuminate when you step on the brake pedal? There is a safety feature that will not allow the shifter to move without applying pressure to the brake pedal. It is a solenoid wired to the brake pedal switch through the brake relay, which is protected by a fuse in your fuse panel.

Lets start by checking your brake light switch.
Your car has a switch on the brake pedal that not only makes the brake lights come on, but also tells the transmission it can shift out of park.
This really may be 2 separate switches, but should be under the dashboard and both should "open" when you push the brake pedal down.
Take a good flashlight and look.
The switches are small, about the size of your thumb, and both should have 2 wires attached to them.
Be blessed.

Let me just say that I learned how instead of depressing the brake fully, I could simply press ever so lightly on the brake and smoothly shift out of park and into reverse or drive

Is your car Parked on a hill. Do you use the E-brake.
1st. Make sure you, press the bake peddle.
2nd.If the car is parked on a little hill facing up or down
you'll need to move the car a little. Up or down.
3rd. When the car is parked not level the transmission
parking PAW or PARKING lock inside the Transmission
may have to mush pressure on on it to move easily
So, that is probably the problem. Move the car eighter way
to relieve the presser off the parking Paw. When parking the car
when stoped, Leave your foot presure on the brake pedal.
set the E- Brake then put, the trans into PARK.This way
The presure, in the trans parking lock is not to tight.

So I'm guessing that when you put it in reverse and it won't move. If you put it in 1st it moves but won't shift to 2nd? And it rattles. And since you have a 4.9 in it the transmission is a 4T60E. I am going to guess that you broke the reverse reaction shell in the transmission.

I had the same problem with my 98 Cadillac Deville. I changed the power steering pump and the hose that runs to the rack. The problem was solved, loud noises and whining stopped.

Yes, most likely a fault in the auto transmission, and the car has shut itself off to prevent further damage.