My 2003 A4 1.8 has just started acting up. Can anyone help diagnose this problem or make a suggestion on what I should do?

Symptoms:
1. When turning the car on, it doesn't have a solid idle and wants to stall unless I give it some gas.
2. When driving the car (I noticed this problem while driving) it seems to misfire especially when at the bottom of a gear.
3. A "popping" noise is coming from the engine, not sure if this is the car misfiring.
4. Check engine light comes on solid, every few minutes it will flash for about 10 seconds.
5. Car seems to idle slightly better when in neutral.

Video of engine noises - http://www.youtube.com/watch?v=zOJqekFb1aY

Other:
1. Slightly low on oil (not enough to give a check oil light). I am going to top it up today.
2. Bought 1 new coilpack. Going one at a time, I replaced an existing coilpack and turned on the car to see if symptoms were gone. After testing each coilpack the symptoms didn't disappear. (Please note only one coilpack was replaced at a time.)
3. Going from front of car to back of car, coilpack 1 and 2 were relatively clean, 3 and 4 were quite brown and looked very used.
4. I had coilpacks replaced about 4yrs ago, but i am not sure if they replaced 1, 2, 3, or all of them.

Thoughts:
1. Maybe I should buy a second coilpack to see if two of them are bad? Are multiple coilpacks known to go bad at the same time?
2. Someone suggested I try putting some dry gas into the gas tank.
3. Change the spark plugs? I don't have a ratchet extension long enough to remove them at the moment.

If anyone can throw me some suggestions on what might be happening and how I could fix this problem I WOULD GREATLY APPRECIATE IT.

Thanks,

Tim