4th gen is my brothers. I’m a 3rd gen guy. He parked it at my house. I cranked it drove it around, sat for 5 days refused to start, battery died, charged battery overnight crank and drove it next to my barn. Note when it ran it ran fine, smooth no issues. Parked by barn and there it sits. Refusing to start. New fuel pump as we suspected no fuel, crank no start. Checked coil packs,(recently replaced, mechanic said the plugs were fouling out and ruining the packs? My brother is not mechanically inclined) coil packs didn’t produce much spark, ohmed out can sensors found a bad one, replaced. Crank no start. No spark. Swapped crank sensor. Crank no start. Can’t check for spark without buddy. Moved around relays at random, they all cycle when touched to 12v and all the fuses under the hood checked good. Crank no start. Engine responds to a little ether, but just enough to cough and die. What’s next? Any help appreciated? Don’t get no spark with new coil packs, plugs looked decent.

If you are getting a sputter with the ether, sounds like you are getting spark but no fuel. Do the plugs look dry after trying to start it? They would be wet if fuel was getting to them I would look at that fuel pump that was replaced, relay and EFI fuse. I would think you ought to hear a bit of a hum when you key on before starting as the fuel pump kicks on and builds pressure - might try listening with ear to the fuel tank door. This is coming from general experience, not specifically 4th gen. All I got at the moment.

I would disconnect the battery for 15 mins then try again and see if any codes are stored.

Also check the battery is giving a steady 12.5V or so and the terminals are tight.

You need to verify fuel pressure or at least listen for pump noise.

Any aftermarket alarm install?

Just hit the unlock button twice and see if it cranks again. Maybe it got a starter kill relay wired up from the aftermarket system.

Also, any gas in the tank?