Why does the engine idles rough?

How long since a tune-up? Any applicable trouble codes? To check for codes, at the least, you need an obd2 code reader, that will work with your vehicle. Use a gage and check fuel pressure, not only check for correct pressure, check that the pressure will hold, with everything off. I haven't looked at your specs, usually the pressure shouldn't drop like a rock after the vehicle is turned off.