My 2002 a4 18t is still throwing a p0171 lean code.
I have replaced

all of the check valves and hoses
pcv and assorted hoses
front o2 sensor
exhaust manifold (cracked)
turbo (cracked)
apr diverter valve
fuel filter
cleaned the MAF

the car has been modded
apr1+ w/injectors
test pipe
apr DV

I have scoured the archives and the net and I'm not sure what to look at next.

rear o2 sensor
replace the MAF
evap system ie charcoal canister (where is it located)
are there vacuum line associated with the evap system?
could they cause a lean condition?

Any help would be great. I live in Carson City NV if there are board members in my area please send me any suggestions as to reliable shops or someone with a vag com

Thanks