Thanks for the pieces of advice. Let me try to elaborate although I'm not too technical.

By dreadful I mean that the acceleration of the car isn't smooth. The 'thunk' is the car losing all power after 1-2 seconds of starting off in 1st gear, and the relative pressure on the accelerator pedal to cause this is probably quarter-pressed. Could you tell me how to tell if all cylinders are firing? Even when the car has been going for 5-10 minutes there is another symptom, which is more evident on hills. So I turn right up a hill (with increasing gradient) already in 2nd. As the gradient increases I press the accelerator to keep the speed and the power drops for a few seconds and then kicks in reluctantly. On a flat this may happen going from 2nd to 3rd; the power (thrust) actually drops before picking up.

In the first minutes of driving off this loss of power is most obvious because the car would actually come to a halt if I didn't press the clutch in and save it.

Could you elaborate on the process of turning the distributor, for a newbie? Thanks a lot.