Obtain a listing of your current service trouble codes which may point to the trouble.
More than likely you might want to consider either or both of these possibilities.
1. Replace your fuel filter.
2. Replace your fuel pressure regulator.
You can replace the above yourself if you have basic mechanical automotive skills and simple tools.
3. Least likey is that your fuel pump is working intermittently.
The service trouble codes would likely tell you that.
You might also want to check any fuses or wiring connectors.
Cadillac has fuses under the hood and in the rear trunk area. The Trunk area fuses are behind the carpeted padding behind the rear seat on the drivers side.
Both can be done yourself if your the least bit talented with tools and getting a tiny amount of grease on your hands.
Important: Only Work on these with the ignition turned off and cold. Otherwise fuel might leak on a hot item and cause a fire or explosion from the gasoline vapors.
When replacing both remember to release the fuel pressure first. Their is usually a valve at the end of the fuel rail with a covered scharder valve to do this. Just remove the cover, save in a safe place for reuse. Then with a small nail or similar item press in on the small pin to releive the pressure. ( It's similar to letting air out of a tire ) Make sure to have a rag and small cup to catch any fuel that leaks out. Once the pressure has been released fully, you can put the cover cap back on the schradrer valve. Now you can work on replacing the parts. Fuel pressure is restored when your done by simply restarting the engine.
The fuel filter is located on the bottom of the car frame rail just under the rear driver side car door.
The fuel pressure regulator is connected to the fuel rail lines toward the rear side of the engine manifold cover . If you have nylon rail fuels use the Fuel Pressuer Regulator for Nylon Fuel Rails. If you have Stainless Steel Fuel Rails use the Fuel Pressure Regulator for Stainless Steel Fuel Rails.
See the attached pictures.
Again, wipe up any spilled fuel and let vapors dissipate before restarting the car.