mileage has gone down in the last year

Within the last year or two my average tank has went from around 43 to 38 mpg. This is driving in the fast lane and moderate acceleration. Driving easier i have gotten as high as 48. Its not too bad of overall mileage but i rarely do 600 miles per tank anymore venting the tank. I havnt done any additional mods than what is in my signature during the time frame of the decrease. I just checked the settings on vag com. The timing is one tiny dot above the green line and the IQ is around 6. It is kind of smoky when i accelerate quickly before the boost builds up. The car has 175k miles and has been a little bit of an oil burner before and after the change in mileage. Im currently looking at the condition of the MAF sensor cause the actual MAF is higher than the requested reading. Also the EGR is leaking out of the weep hole and making a mess on my valve cover. Im not sure what else to check

http://forums.tdiclub.com/showthread.php?t=342274

Good place to start.

I'm sure you already did, but do the easy stuff you would normally do. Check tire pressure, change fuel filter, change oil. Perhaps check the turbo veins are fully operational. I had the same thing happen to me a year ago. Everything in vagcom was within spec. Checked the normal maintenance stuff and one of those solved my mpg issue