2000 Mazda Protege car want crank

Engine Performance problem
2000 Mazda Protege 4 cyl Two Wheel Drive Automatic

My daughter brought me the car after it got hot and shut off. After letting it cool I put water in it and got it home. Later I put a new much needed thermostat in it. I then crank it up and ran to my neighbors to see if he could help me find where it is leaking. We found out that I needed a new radiator. I Cranked the car back up with a little assistance of starting fluid. It ran good, and I drove it back home. Let it run for five minutes or so, turn it off waited ten minutes and tried to crank it up and it started very easy. I shut it off and the next day replaced radiator. I got everything back on like it is supposed to be. It will not crank up. I pulled two spark plugs(one at a time) and checked the sparks. Both plugs started off with good sparks and then they stated getting weaker and weaker. I sure could use some advice.