As the title says, my Volvo is running a bit rough but only after it sits for an extended period. When I drive it consistently it's great but when I start it after resting for a couple days it has a difficult time turning over right away. Once it does turn over it cycles between running fine and then feeling as if it is misfiring. For the first couple of miles it runs fine but will have a rough idle when stopped and then slowly normalize. Any ideas here? I suspect a loss in pressure but wouldn't know where to start to diagnose/fix this. For a little background the car has had a decent amount of work recently. New injectors, injector housings, replaced air flow regulator, warm up regulator, PCV system and fuel filter.