Driving home today on the highway, slowed down for traffic and then i noticed my car riding rough, loss of power, making a weird exhaust tune, and occasionally a pop. has a rough idle as well, any ideas. thank you... 2002audi a4 V6 quattro

 

i had a similar problem with my 05 a4 2.0t..i took it to the dealer and they said that there was a problem with the fuel canister so they took out my backseats and replaced it. however, i still noticed a slight noise and loss of power. I decided to check my spark plugs and sure enough there was almost nothing left. I replaced them with the E3 diamond plugs and now my car runs perfectly!! hope that helps

 

sounds like a misfire to me and if the plugs have been done less than 20k miles ago I think you need a coil and if you do do all six. Easiest way to find out is find the missing cylinder and swap coils and see if it moves. Thats all the diag I can do without codes.