You didn't specify if it's a L4 Carbureted or V6 EFI.
I don't know much about engines, but if it's a Carbureted engine it is said that you need 3 things to make an engine run: Gas, Air and Spark. The new air filter was not needed to make a test, if you simply remove it it should work, Did you check the fuel tank level?, if you drop a little gasoline on the carburetor intake you can see if it runs for a few seconds. I don't think that all spark plugs can get bad at the same time if it whas working in the morning, at least you should get some explosions, disconnecting the line that goes from the fuel pump to the carburetor and placing it inside a bottle you can see the gas flow, just be careful with sparks, if you don't get flow try check the fuel filter.