99 Sentra engine rotates but will not start

I have a 99 Nissan Sentra GXE with automatic transmission. One week ago the engine suddenly quit on the highway without any previous indications. I tried to restart the engine for a week but it would only rotate but never starts at all. I checked ignition wire spark and timing belt and they are fine. I even replaced spark plugs too. The fuel pump seems to be working and plenty of gas in the tank. Did anyone have similar problem before? Can anyone please offer some advice before I can send it to the dealer? Thanks!

check ecu cables and use a stethoscope to see if the injectors are clicking open like they should