can a cam shaft sensor cause a car to run very poorly and if you are to replae a 4.o v-6 "E" motor is there another year and type that will work if im to replace the motor ?

yes, a cam sensor malfunction can cause a car to run poorly. It sends a signal to the computer which makes adjustments to fuel, timing etc. sorry, cant help on the motor replacement question

Any 4.0 engine from another explorer going back will work (fit) into the vehicle. The problem will be with the electronics. For 1996 there was a 4.0 pushrod engine and a 4.0 sohc engine.