more than likely you have a short in your wiring
usually that problem is attributed to water seeping in to the connections of the computer causing corrosion.The other thing that can fry a computer in your car is welding on it without disconnecting the battery.A bad battery could in theory kill a computer especially if you keep jumping it off and to lazy to buy a new battery.
Have your Throttle Position Sensor Checked. Big cause of this. Do you have any check engine light come on?
Having the speedometer jump and the engine stall in the 1994 Jeep Grand Cherokee Laredo could be a problem with the idle and the transmission. The transmission slipping can cause the speedometer to jump.
Pinched or blocked transmission cooling lines
Loose or worn out serpentine belt.
Yes, if it is leaking and the coolant level is low.
Heater core
Throttle position sensor
the switch board could be bad.
Yes
check the drive axles they could be bad
The back of the ignition key cylinder is probably broken.