I would like to find the cause of my Accord's starting problem.

Randomly and with no consistent pattern, when I turn the key to position 2 I hear the fuel pump, the check engine light goes out after two seconds. I press the clutch pedal to floor and I turn to position 3 I hear the relay click but engine does not crank. I then can do one of several combination of actions such as:

1) holding key in position 3 I release the clutch and press the clutch to the floor and the car cranks over. Might be first time or the 10th time.
2) holding the clutch to the floor and turn the key from position 2 to position 3 and the car cranks over. Might be first time or the 10th time.

Also, there have been times that the car starts on the first time I take key to start position.

It does not matter if the engine has been running and just turned off, running for hours, sitting over night, temperatures in the 80s+ or the 40s.

Today the number of times I do the above actions to have the car crank over has been in the 30 to 50 times.

The troubleshooting done and parts I have changed out to now is the following:

a) check battery voltage (12.5v), individual cell (no dead cells) and battery charging (14.2v).
b) did k-test ( 5v.)
c) check for error codes. Check engine light stays lighted and does not flash.
d) replaced ignition switch and key cylinder.
e) replace clutch neutral safety switch.

Can anyone help with what is the cause or testing to find the cause?

My bet is that there is an intermittent problem with the starter solenoid. The contact ring inside gets severely pitted and the starter motor won't consistently crank. It's easy to test this hypothesis. Perform an ignition by-pass test, by connecting a 12 AWG wire, or remote starter switch, between the positive battery terminal and the "S" terminal on the starter solenoid. If the starter motor consistently cranks, then you know the starter solenoid and starter motor are fine and that you need to focus on the starter cut relay, clutch interlock switch, ignition switch, and wiring. If the starter motor does not consistently crank, either install a new solenoid or, if your solenoid is made by Denso, you can rebuild it. The starter motor itself tends to be very reliable.

If you want to check the starter cut relay, it is located along the left kick panel. It goes without saying, you should clean the cable/connections going to the starter solenoid and starter motor with abrasive cloth and ensure connections are tight.