when you say ecm you mean the box in the air filter? thats the pcm. "power control module."
unhooking stuff make lots of stuff not work, unplug the crank sensor and it will fail to run for sure. crank sensor and the icm (the part under the coils) work together to send the spark out. the icm also has a ground wire thats bolted to the side of the head. if it broke of the car wont start either.
when the crank sensor goes bad it will do the stall start up deal for quite some time, then it will get bad, like wont fire back up for a hour, or a day, or a week later. they never throw a code either.
