Car does not start

When I was driving my girlfriend to work, when I slowed down to turn, the engine shut off, but lights and radio still worked, I had to crank it for ten to fifteen seconds for it to start, it started was running decent, I went to autozone because my oil light was on and they told me that was my oil pressure sensor switch, I purchased that and the car was still not starting easily, but it did start. I got maybe two to four miles down the road and it quit again, I got it to start did this two more times before it quit completely, there was slight smoke from the engine, the car was running hot here and there, but it would cool down, usually if I turned the air conditioner off. Now it will not start, brand new battery, alternator, post connections, and a serpentine belt, and there were a few bad grounds I fixed, anyway, I have fuel at the fuel line, I have air, and my timing belt is spot on, I just do not have a compression tester, but when I try to start it it feels like it is about to start and I hear a pop like a detonation that happened to late, and it almost turns over but does not. Have been stuck for a bit and I do not have money to throw at the car. I need help please and thank you.