1993 Oldsmobile Achieva Cranck sensor

Electrical problem
1993 Oldsmobile Achieva 4 cyl Front Wheel Drive Automatic

Where is the crank sensor found on this motor? The car starts and runs great for a short period of time 10-15 minutes then shuts off and will not start for a few hours or the next day sometimes. When this happens it does not fire at all. I have replaced. Coil packs, cap over coils, plug boots, and ignition control modgel. A friend said it could be a crank sensor so I bought one and can not find it on this motor have looked everwhere on the block.