[scottfab]

If you had not had a past issue with the speed sensor I'd take you down a different path. However you have and it seemed to fix the problem.

I'd start right at the speed sensor connector. Check the mounting hardware on the sensor itself to make sure it's snug.
Disconnect the connector, clean contacts and move the wiring harness around and look for where it maybe rubbing on something.
Physically bend and move the harness around. Even if you don't find the root cause this movement can serve to helpful.
Reassemble with liberal amounts of dielectric grease on the contacts.
If the problem seems to go away you may not be out of the woods if the harness is rubbing somewhere and you did not find it.
The fact that you can shut the car off and restart it tells me you have a mechanical intermittent. (wire open/short)