I am at my wits end.

I have an 2000 Audi A4 B5 atw engine automatic trans. While at idle no problem, while the car is in neutral I can rev the engine or hold it at any rpm and no problem. While driving and the car is under load and under 2000 rpm the car shutters and the rpms jump 200 to 400 rpm. While driving at constant speed there is no noticeable problem. I can feel a slight shutter just before the car shifts. There was a check engine light and emissions workshop message but after I cleaned the MAF sensor they went away.

So far I have replaced the oil pump, turbo, small vacuum lines, coil packs, spark plugs, O2 sensor precat, valve cover gasket. I have tried unplugging the MAF and the problem still persists. I had it scanned at autozone and the only code that comes up is

P1113 O2 Sensor Bank 1 Sensor 1 Heater resistance to high.

I just replaced the O2 sensor could it be bad? I had the same problem before I replaced it.

There is oil on two of the spark plug threads although I haven't checked them since I changed the valve cover gasket.

Could it be a boost leak or vacuum leak?
Could it be the pvc system?

Any help would be greatly appreciated.

 

Update:

after a vag-com it appears that it is the torque convertor slipping.