2006 tahoe is parked on step incline backed in and now wont start

Fuel pumps rely on the gas in the tank for cooling and lubrication. They soon wear out seals running dry. Check that the fuel pressure within factory specs using a gauge.

https://www.google.com/search?q=96+sable+fuel+pump+pressure+spec

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Bad fuel pump replace it

Low on fuel

Ruined an already worn out fuel pump

The regulator is probably under the intake manifold along with your injectors...the pump is in the fuel tank and the filter is usually on the firewall...

had the same thing happen to me. dealership told me it was a safety feature that when it runs out of gas it wont start again without clearing the code so they said. I hade mine towed to dealership and let them mess with it, cause I also put more gas in it and eventually drained my battery trying to start it.

If the engine cranks the starter is doing its job.
You would need to check for fuel pressure at the injectors.
Its possible the pump was clogged up or overheated when you were driving it low on fuel. The gasoline keeps the pump cool and lubed.
The only fuel filter for your model is inside the gas tank.

is the fuel level low? when parked on incline the fuel will go to front or back of the tank, if the level is low it might not reach the pump which is usually close to center

The incline is apparently enough to have the feed from your tank exposed to air and not gas. If you can let the vehicle roll back and turn the wheel so your facing in the opposite direction before you attempt to start it again. This will allow the fuel to feed out of the tank like it is supposed to and should start fairly easily. Since the line is empty now, it make take a few seconds more than usual to prime with fuel and crank. Parking on inclines will get you if they're steep and your tank isn't full. Just remember this and next go round if you have to do this again, make sure your vehicle is parked in the opposite direction and the feed tube out of the tank will still be covered with gas.

It might be the fuel pump or might be the distributor.