Malibu went through hurricane Katrina, was parked on incline and flooded to botton of dash. Engine OK, Battery is completely dead, when jumped it starts and runs for 2 or 3 seconds then dies. Gas gauge reads completely empty, needle is sitting on the pin and never moves and tank is at least half full. Have changed computer and makes no difference. Can hear fuel pump running for 2 or 3 seconds when key is turned on. Everything else works fine, windows, stereo, blower etc. Would really like to save it as it only has 35,000 miles on it, took 3 years to work the bugs out of it, and come to find out the insurance people had talked the wife into taking total coverage off after it was paid for.

Any help would be GREATLY appreciated.

Many things. First, get a new battery in it. Secondly, replace the alternator. Replace the oil. Then, youll have about a 33% chance that it will still be salvageable when it starts. Any long term water exposure is gonna play hell with the car. The wiring, the seals.... you might get lucky, but dont count on it.

Scrap it.
If this vehicle has been flooded, your problems are only beginning.