96 Montero LS

I have a 96 Montero LS that I just had the water pump and timing belt replaced.....I now have virtually no power, and a helluva spark knock (not correctly timed).....the mechanics tore it back down and said that all the timing marks were correctly aligned.....now, my question is: with the timing marks aligned, how does one set the timing to 5 degrees BTC as it states on the tag underneath the hood? Is it with the Crank Angle Sensor???? This car has a coil pack and not a distributor, and I think the whole problem may lie with the assumption that the mechanics accidentally moved the sensor when replacing the belt....any help is greatly appreciated!!!!! Thanks much!.....Ken