1993 Mazda 626 no spark

I have a 1993 Mazda 626 LX 2.0 4 cylinder with a manual tranny with 155,000 miles. It just shut off while driving after I noticed my rpm needle fludder around a second then go back to normal. After checking things over I had no spark. I changed the rotor inside the distributor cap and the cap because the old rotor was lose on the shaft. After that it ran fine for about a mile or so then shut off again. Again no spark from the distributor. This time I bought a new distributor. I put the engine at top dead center checked the # 1 piston was up and the rotor was facing the # 1 peg in the cap and installed the new one. Still have no spark at all. I am confident the car is in time. There is 12 volts going to both the large and small connectors on the back of the distributor when the key is in the on position. The mazda dealer said that engine doesn't have a crankshaft position sensor down by the crankshaft wheel. I have no more ideas. I still have no spark. Is it possible I got the wrong new distributor? Please give me something to look for. Anything will help. If you need any further info, feel free to e-mail me at minimazda323@yahoo. Com. Thank you for your time,

Desperate with no spark in Florida