Cadillac Repair: 1998 Cadillac deElegance Starting trouble, combustion chambers, cadillac sedan deville

Question
I have a 1998 Cadillac Sedan Deville DeElegance with a Northstar engine, 92,000 miles. The engine turns over but does not always start, and sometimes when it does start it runs real rough like it's not getting enough gas.  They have changed the fuel pump, put in a new relay switch, and checked fuses. What could be the problem?

Answer
Are you getting adequate spark to the spark plugs ?.

Is the engine cranking over fast enough (faulty battery?)

Can you hear the fuel pump run for ONLY 2 seconds when you turn the ignition key to the ON position without attempting to start the engine ?.

Could have some leaking fuel injectors that are flooding the combustion chambers which will cause hard starting .