car wont start, could it be what?

[braq]

Hello,
My car was running fine until i shut it off. and tried to start it. it wont start. the starter crank very very slow, like its not having enough power and all the light dims. i thought its was the alternator, so i got a new alternator. the car is still doing the same thing. so i bought a new battery. and the car is still doing the same thing. and finally i bought a new starter and its doing the same thing..now i don't know what the problem is. my guess maybe i have a bad grounding to the engine or something. the start is trying its hardest to crank. maybe i have a crack on the flywheel teeth to the start..