91 regal starts but won't run - 1991 Buick Regal

Security light lit on the instrument cluster ? Anti-theft system will disable the fuel injectors if it has a problem

they have a relay

Sounds like a relay or coil failing.
To proceed you would need to find out if you are loosing spark to the plugs or fuel pressure to the injectors when it won't start.

Check your fuel injectors

After changing the ignition module, you may have broken the communication between all the components in the anti theft security system. This is common on GM antitheft systems. Check out this link for how it works and solutions to security problems. http://vatspasslockpasskeysecurityhelp.yolasite.com/

replace the ignition module,under the coil pack.

The cam sensor is most likely the cause.
The sensor is getting hot and shorting out intermitantly. I would have the vehicle check by your local mechanic.

check the batt. connector

hi is it automatic and won,t start that mean won,t turn over or turns over but won,t start ? how occasional yates210456

sounds like an ignition module