Get a diagram for your vaccum lines and check all of them. This is where i would start from what ghost said.

 

On a tip or auto car, limp mode will cause the TCM to keep the car in one or two gears, usually 2nd gear. You won't have tip function, cruise control, or torque convertor lockup.

For example, if you have a bad MAF, most auto/tip cars will put the trans in limp mode to avoid transmission damage. The MAF is the load signal for the TCM. If the load is incorrect, the car doesn't know when to shift, so the TCM will stick your car in one gear and leave it there.

The DTC 1129 is "Long Term Fuel Trim Multi. Bank 2 System Too Rich."

Multiplicative, or Multi, means off idle (under load) adjustment. The code is telling you Bank 2 is running rich. To accurately diagnose this code, you really need to know your O2 sensor readings from both banks as well as the fuel trim readings from bank 1. This code does not point to a vacuum leak. The car is pulling fuel to compensate, not adding it. You can see how the car is actually running with O2 values at hand.

If you have a bad MAF, in general, you'd see a common code for both banks (P1127 and P1129. If Bank 1 fuel trims are also close to the maximum adjustment, you might be looking at a sensor issue. I believe you need measuring block 32 if I recall correctly.

The code P1141 is indicative of the ECM getting two readings from two different sensors that don't add up. In other words, if your MAP sensor says there is this much air and the MAF says there is a different amount of air, the ECM says, "hold, on... who's right?!?" and thusly, the MIL illuminates on your dash. The cause of this code is also likely responsible for your limp mode situation.

Without further info, it's hard to say what the issue is. Knowing Audis and the given info, an educated guestimation would be a bad MAF. Open up the airbox and check for an overly dirty filter or debris against the MAF housing screen. Clean the MAF with a MAF cleaning solution (non-reside electronics cleaner), erase the DTCs and drive the car. Let us know the results.