94 ford ranger temp rises and falls constantly

The gauges rises fast and drops fast because there is air in the system. I would fill it first/purge the air out as it is running. If it still discharges on the floor, you might want to change the T stat and or water pump.

Check the coolant level, add some if needed. If you never bled the air out or flushed the system with new coolant, that would be wise to do. Air pockets in your coolant tank can cause pressure and Temps to rise. Make sure your fans are kicking on, once your car reaches a certain temp, it hits a temp switch telling the fan to kick on. Could be faulty coolant temperature sensor as well

You have to make sure the thermostat is working properly and is the correct one. Idle the vehicle for about 20 minutes and then feel the upper radiator hose. It should be hot to the touch. Drive the vehicle and when the temp gauge falls to 'cold' stop and feel it again. If it is much cooler to the touch than before the thermostat is defective or wrong.

AHHH did you check the fuel filter, 80% of faulty fuel pumps that I have worked on have only been the filter

can you see the fluid circulate? with the cap of(radiator cap) see if the fluid moves around.
does it overheats? give me more info

The smoke could be the water boiling. Although it is possible that you blew the head gasket, if the vehicle overheated badly, It is also possible that you still have some air in the system. Replace the thermostat and seal /gasket and run the vehicle while adding coolant. Do not install cap on until both houses upper and lower are hot to the touch. This is an indication that the thermostat opened and coolant is actually circulating. Good luck.

have you checked your water pump?

I would check the coolant temp sensor.

Dis brakes have residual pressure thar keeps the pads in constant contact with the roter.It is very light contact, so not to worry. If left is not in contact with rotor then chk it for loose wheel bearings.

sounds like you need to flush the cooling system it is a common problem on those Tauruses