What could it be?

[PM1990]

I have a 2019 DEFENDER max HD10 lone star edition. It has 231 miles and 51 hours on it.I filled it with fuel earlier today before using it. All of a sudden it started sputtering and started to lose power when on H also on L but not in Reverse. It then flashed low gear on me and had an green (!) pop up then went away. When I have it in park it sits on a rough idle and I press the gas and it’s a hit or miss sometimes it accelerates and sometime it doesn’t! I’m new to this and have no clue what it would be? Any help would be greatly appreciated. 

[Steelslinger]

Bad fuel would be my first thought if it started right after you filled it up. I'd drain the tank and get good fuel from a different source than the last fill up and see what it does.

[Andystoy19]

Likely water in the gasoline, try and get a sample off the bottom of the tank and put in a clear glass jar. If the fuel has ethanol in it it may have absorbed some condensation while it was stored. If you want to inspect the tank you can get access on the passenger side of the engine compartment there is a large cap on top the tank that can be unscrewed and will pull the fuel pump and filter sock. This shouldn't be necessary unless draining the tank and putting in some fresh fuel doesn't work?🙂