I have a 2004 Honda Accord and sometimes when I try to start it won't start and other times it works best kind but it's like the start motor is not working everything still works in the car when I turn the key to the on position but it won't start I changed the ignition I changed the neutral safety switch I changed out the alternator and start motor and I still can't figure out what it is anyone able to help

 

Are all your connections clean?
When it will not start, does it make a noise, do any lights dim or anything?

Usually bad connections.