98' w/3100 - no spark, randomly starts

To start off, months ago I had the current engine installed by a shop after the old one died of neglect (previous owner.) When I got it back from the mechanic it was running strange so I started rooting around looking for loose connectors and such. Turns out the crank sensor that plugs into the ICM was disconnected, and the unit below that was disconnected as well. After plugging them both in it ran better.

Driving the car for a few weeks it would die randomly when coming to a stop, but always started back up. Now it won't start at all. Aside from two times it fired right up for some reason and I can not pinpoint why. Both times I turned it off and immediately tried to restart it with no luck.

I know the mechanic did the CKP relearn thing because I was there when he did it just before I took it home. Could that have something to do with what's going on?

I've done a bunch of testing and diagnosis but can't find any issues. The ICM is not providing signal to the coils. I replaced the ICM with a brand new one which did nothing.

I'm getting fed up and am about to take this to a mechanic. Any ideas?

Well after some more time spent working on the car I decided to start over from the beginning. In doing so I realized that when I measured the 7x crankshaft position sensor before I incorrectly converted .025 volts ac to 250 millivolts ac. I don't know what I was thinking, but this is of course only 25 millivolts. I replaced the crank sensor and it fired up immediately. Just posting results to help anyone in the future who might stumble on this.