1995 BMW 318i Engine stalls, does not start

My 1995 BMW 318ti was running perfectly okay, but suddenly the engine stalls and it won't start. The ignition starter just cranks the engine. I checked the fuel pump and it was pumping fuel when I switched. The ignition starter. I had it towed to my home and worked on fixing the problem. I was told by a friend to check and replace my crankshaft sensor. Since it was an exercise of trial and error, I sourced a used crankshaft sensor and replaced the one in my car. I was able to get the car running again. However after a couple of days of driving the car, it developed the same problem. I took out the #1 high tension lead cable with the spark plug fitted on it pointing the end to the engine metal body. I switched the ignition starter and cranked the engine to check if there was electric current running into the system. There was current and the engine in fact ran although very rough since one of the plugs was out. I placed back the spark plug and high tension lead wire and started the engine. The engine started and ran smoothly again. I was able to use it for another 2 days with seemingly no problems. But again, the engine just stalled when I was driving it. It had the same problem as before so I did the same process of removing the same high tension lead wire and spark plug. I checked if there was electricity as I cranked the engine. Same result as before and the engine started. I was able to drive the car home. However, In the process of driving it back, the engine died down twice, but luckily, I was able to start the car without doing the same check process earlier. Please help. What could be the problem of the car.
Looking forward for your reply. Thanks,

sonny