Disconnect the crank sensor, pull out a spark plug, stick compression tester in spark plug hole, crank engine, compare results to OEM range. Do this across all cylinders. *If you have a bad cylinder do a wet test. Just add a few drops of oil to the piston before testing.
Cylinder leak down - acquire cylinder leak down tester>pull the spark plug>put engine at TDC>insert cylinder leak down tester>zero gauge>add air pressure>measure loss> should be less than 20% air loss.
That simple.