What needs changed or fixed if my 91 ninety eight olds will not start or even fire?

its possible. to know it will have to be checked out from the crank and cam sensors and ignition module to the ECM to know for sure.

Possible faulty crank sensor or idle speed controller, fuel pump relay, or ignition module. Get a data scan and see what's sensor might out of range or defective. Check for clogged fuel filter also.

My 1997 Buick Lesabre Custom died on me when I was on the road. Turns over easy without start?

The spark and fuel both get there reference from the crank shaft sensor , so as long as the crankshaft is turning and the sensor and module are good you will have spark and fuel, it sounds like one thing you are missing is compression I think you should see if you have lost a timing chain, does the engine seam to be turning over at a very fast speed? pull a spark plug and check for compression.....SORRY TO BE THE BEARER OF BAD NEWS

Generally it is the Coils or the ignition control module that needs replacing. Hope that helps.

cam sensor is only half of the cam circuit, the other half of the cam circuit is the magnet on the timing chain. the cam sensor reads from the magnet every time the engine completes a revolution,
what happens is the magnet on the chain will break into smaller piece which makes the sensor harder to read every time the engine make a complete revolution.
most likely you'll need to replace the timing chain to fix this.

Sounds like crank sensor located behind crank pulley,or possible crank pulley comming apart.common

have you checked for that relays and regulator?

I had the same thing happen on a 91 Olds 88. Replaced crank shaft position sensor, coil, and ignition module. That solved the problem. I think the culprit was the CSP Sensor, but changed all three so can't say for sure.

Is the batter cable grounded properly?