Hello new to the board here and having an issue with my impreza, I just picked up my car after it has sat for better than a month and not sure if the battery was disconnected or not. I had moved to Alaska for the military and it sat as I was traveling. It now is running really rough at idle and throwing misfire codes for all cylinders. I ran it around for about 30 miles hoping that it may need to just reset but no luck. It seems to be firing properly when I'm accelerating and driving down the road but nearly dies when I stop and try to get started again. Any help or a point in the right direction would be awesome.

How old are the spark plugs? Fuel filter is another possible culprit.

Not sure but it seems odd or coincidental that it just started, I plan on running the standard maintenance things like plugs ect to start. I'll have to do the filter as well

Any evidence of mice getting on the engine and chewing the wires? They like spark plug wires for some reason. And a car that sits for a while looks like a good home to them.

Still on the old tank of fuel? moisture/phase separation in fuel? maybe try some HEET.

Thanks you for the info everyone, I figured it out with a bit of Internet sleuthing. It was the egr valve, the little plunger was carboned up so I cleaned and lubed it and the car runs like a champ!