I tried to be careful and to observe when does my car shakes, and I think that it does it when Air/Fuel gauge reads on lean, few minutes after the car was turned on, sometimes it shakes also when gauge shows optimal but is less noticeable at this stage... (strange the gauge never goes up to reach, is this normal?)
It's strange to me too if the gauge neves shows rich readings.
At cold engine (coolant<40*C) it sholud show rich readings
continously. Try to preheat the sensor with ignition on for 40sec,
before starting the cold engine, then check the readings.
At hot engine over 4500RPM with the accelerator nailed to the floor
it should show rich too (AFR lower than 13.5).
If the Weber engine management's lambda sensor input is connected
together with AFR gauge to the oxygen sensor's signal output, it may
alter the gauge readings, because the engine management sends a
small bias voltage towards the sensor.
The theoretical top speed for an 1.4IE with original gerabox
and the factory tire sizes at redline is:
190km/h +/-4km/h (at 6500RPM) so i think it's not impossible
The rev counters are usually inaccurate because of the small calibration
pot inside the rev counter become defective in the S3 33s (mostly after
six years of service resulting lower readings at the higher RPM range).
I used to replace them with fixed resistors during the recaibration process of the
rev counter. I'm using a signal generator and an oscilliscope to this process.