Have a cranking issue,once the car warms up it's hard to crank or it wont crank

What is your question?

ive changed plugs,distributor cap,rotor,wires,oil filter for the oil and air.once i start in the morning it cranks,during the day once its warm sometimes it turns over and over but wont crank ive checked everything that i know! it seems that the heat is affecting it somewhat,because as long as i don't wait more than 2 minutes to restart it's ok but oncce it sits its hard to start