I have a 2000 dodge ram 1500 quad cab, replaced the clutch fan three times, the transmission, and the water pump. Now there has been 3 times when i have went to the truck and tried to start it and nothing. everything is on and the battery is good. then i come back 30 minutes later and it starts. the truck will go months and do it again, right now it is in the shop and they say nothing is wrong with it. has anyone had this problem or know what it might be.

You turn the key and nothing happens? Or you turn the key and it just cranks and cranks?

When I turn the key on nothing happens, the truck will not even crank. but I can come back to it later and it will turn over and fire right up like nothing is wrong with it. It has been in the shop and has started everytime so they as usual are telling me nothing is wrong with it. Could the starter relay switch be going out? or could the fuse in the fuse box under the hood be going out, or should i think about getting a new ignition switch in the inside of the truck.

maybe your neutral start switch or wire to it if its an automatic