VW Jetta. all 4 cylinders misfiring need help
 

I Have a 2017 VW Jetta Sport. Its misfiring on all 4 cylinders. Coils and spark plugs are good. I am confused, Fuel pressure at start goes to 80PSI but after car is running for a minute the fuel pressure gauge shows that the pressure is going to 30 PSI. Changed Electric Fuel Pump in the tank and the issue was same. no change. I have spent hours trying to figure this issue. Need help.