Yes, the check engine light does stay on while driving. I haven't had the codes read yet to see what the exact problem is.
I have also had problems with the cruise control as well. That has always been bad since I purchased the vehicle from a friend two years ago. Up until now, I haven't had a check engine light or any other problem with the vehicle, it has been quite reliable for a chevy with 175,000 miles on it.
I'm not so sure that the 97 Lumina, or at least this model ( 4 Door V6, LS I believe) has a speed sensor with the gear attachment. The sensor seems to be reading magnetically; as the tip of the sensor that I pulled out is magnetic.
There is no sign of another piece that broke off. This is a weird sensor as all my other vehicles, 95 and older, have the sensor with the gear.
I searched for pictures online and they all show no gear; must just be an advancement in speed sensor technology, possible more reliable.
Thanks again for all your help.