Car turns over, but will not start

I had bought six new spark plugs, (manual recommended) new plug wires, and cylinders one and three was still misfiring. so I got new cylinders and car ran great! Only for about four day's though. all of the sudden car started lugging down and running rough again. Now, it will not start at all. It died out while driving and my dad started pulling it back to my house with a rope during the tow I tried starting it and it did start. I drove it the rest if the way home. But now, all it will do is turn over, but wont start. When I turn the key off after cranking it, it sounds like it was going to start, it makes this weird puffing sound (I wish I could describe it better) kind of like a big puff of air escapes from the engine and out the muffler or something, then it just dies.
I am at a loss, I cannot think of what it could be! Oh, one thing I have not mentioned, do not know if this would have anything to do with what it is doing now, but, I have not had an air filter on my car for quite some time now. I know, that is not good.