Engine won't crank over sometimes

Just to add to this one if its not cranking over meaning the starter is not working to spin the engine over randomly then the most likely cause is the starter. The clutch interlock switches hardly ever fail. Its common for the starters to fail though. Do you have a test light or multimeter for testing?If so we can test the clutch interlock switch to see if the problem is inside or outside the car.

Those starters arent that hard to change for the top bolt I use a 4 inch long 3/8" drive extension with a 13mm wobble socket. You can test it in the car when it wont start what usually fails on those starters is the which is like turning off the switch to the starter. When it doesnt to test the start you would see if there is power to the small purple wire on the starter. If you do bad starter. As far as testing the clutch interlock switch when it wont start make sure the car is in neutral and ebrake is on. Then there should be power going into the yellow wire into the clutch switch with the key in the start position. The yellow wire comes from the starter. You should also have power to the purple wire coming out of the switch with the key in the start position. Ethier way your going to have to change that switch if its broken because its a safety hazzard. The switches are cheap there under 30.