The final test run was done an hour ago. The result was fantastic. Not a trace of sluggishness, and it was prompt on response.
The dist. cap was the culprit, but along the diagnosis, we have now a clean fuel line.
You may recall that I commented earlier (through a different thread) on how the engine (on an Italian tune-up) blows up some black smoke as if coughing on a choke - and after several blows, the engine is fine without the smoke. Well, it looks like the dist. cap replacement also cured that black smoke emission for now.
After a few more days of running and if everything is well, this would be the final post of thanks for all your comments.