While the PCV and PTC nipple are important and need to be cleaned out, if you have already determined that the vacuum lines are all intact and the elbows are not leaking air, check the exhaust for leaks before the front O2 sensor. A leak in the down pipe, a leak just in front of the cat and sometimes a minor leak at the rear O2 sensor can cause bad readings and make the engine run rich.

Check all of the intercooler pipe fittings and make sure they are snug all of the way to the throttle body. How about the air pipe from the air cleaner to the turbo, any cracks?

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