1999 A6 Quattro 205,000 miles

I need to get my car to pass State emissions here in Utah, but I've got a problem that even the two garages I've been to are having trouble with. When tested the following codes come up:
p1338
p0501
p0455
p1136
p1138

and when retested later in the day, after one garage cleared the codes
p1338
p0441

I don't have a lot of extra cash lying around and I want to fix this myself if possible...anybody have any input about what the main culprit might be?