Engine coolant temp sensor fault, could be the sensor or loom fault. The ECT fault can cause major running issues if the reading is out of range, the mapping (if you have AUM) have a lot of offset maps related to engine temps. The snap on tool should have the generic pids which will pick up the real time data from the ECT sensor which will show you what the ecu is seeing, check it from cold and at running temps.
The problem with the performance & being lumpy could be unrelated to p0116, you could have a few other underlaying issues which wont always show up on vagcom.
The first test we always do is disconect the MAF and take the car for a drive to see if the generic sensor mode makes the car run better and smoother... if not then a live run logging session is needed.
What Spec is your car? stock or remapped? tuning mods? Where are you from?
Nick
