A friend of mine purchased an '07 A4 2.0t Quattro about a year ago and making monthly payments. Aside from having a very minor external oil leak, the car ran fine. On his way home from work one day, the engine suddenly stopped while driving on the freeway. He was able to get the car running again, albeit very roughly.

The only codes that I could pull off of the car (3) indicated random misfire, misfire on cylinder 2, and misfire on cylinder 4. I put in both coil packs from O'Reilly's, replaced all the spark plugs, and soaked the cylinders with seafoam overnight. Owner comments it sounds like it's running only a little better, but unfortunately both misfires are still continuing. I did examine the old plugs and they had very noticeable black oily crusty residue on them, each plug looking worse the further you move to the front of the engine. After several times of running the engine, the new spark plugs 1 and 3 had white residue, while 2 and 4 still looked fine but smelled gassy. The 6in tube after the exhaust manifold (which I'm assuming is the cat) also started glowing after running the RPMs up to around 3k

The owner says that while the car has always burned a little oil , he never noticed any kind of progressively deteriorating running conditions, this just happened suddenly. He is on an extremely tight budget, so I'm doing the work for free (he's a very close friend) and we want to be careful to avoid buying unnecessary parts. I've researched all day yesterday and this morning and noticed this is a common issue, but has several different fixes.(faulty injectors, shaft follower, timing, electrical connections, egr, pcv, valve buildup, etc) I guess I'm hoping with the info I've provided, someone can point me in the best direction rather than just giving me a list of possible causes. As this is my first time working on an Audi, any help would be greatly appreciated. Thank you!

 

Following because mine is currently in the shop with misfire gremlins as well.