Ruff Idle and loss of power

I have a very basic 2000 Accent and when I first turn over my car it seems OK. When i put it into drive but don't take my foot off the break it sounds a bit ruff. When I do take off first thing in the morning it drives alright for about 30 seconds, then I feel power loss for about 5 seconds, then it picks back up again.

Also, when sitting at the lights for a long period of time the engine sounds fine then it seems to hit these really rough spaots for a bit the works alright again.

Is this something to do with fuel injection or bad spark plugs?

Chef