You might need a new u joint.
replace it
3500.00
that depends on the motor that it has.
above the oil filter ,to the left.
maybe ablown head gasket
above oil filter.
below top end of radiator hose.
Go to Autozone and get a haynes repair manual,it will show and tell you how.
that would be the throttle sensor.
in front of the right rear wheel attached to the frame
That info is on pages 18 and 19 of the EF(Engine fuel) & EC(Emission control)section of the 1987 Nissan Truck/Pathfinder service manual.
probably 4 quarts. Any auto shop will tell you