Audi Repair: Audi A3 V5 1.8, mass airflow sensor, vacuum problem

Question
I have a Audi A3 with a V5 1.8 petrol.
This car runs fine for weeks and then goes on the blink.
This is what happens:
1. Hard to start and idles low when running
2. A/C cuts in and out while highway driving
and lacks cold air
3.While driving, the car stutters when I shift the gears at 2500 to 2800 rev

Two days latter it is running fine.
Is there an air flow monitor or could this be an vacuum problem.
Thanks
Eric

Answer
It sounds like a poor connection somewhere, maybe on the mass airflow sensor.  The AC cutting in and out, does the system have enough of a charge in it, does it work when you switch it on when the engine is working well?  If the car stutters when givng it gas then the mixture may be incorrect, have you run diagnostics on the car?  I would get a VAG-COM readout first.  Let me know,  Jan