Most Q-Jet problems are caused by the last guy who touched it. Very often they were "trick of the month club" subscribers who think they have some super secret insider information about how to do one and they know more than the company who engineered and built the carb. They're always wrong - on both counts.
Cliff's book is very good. If you can find an original unmolested QJet (hint - scour your favorite salvage yard for one from a full size "land yacht" car, not a performance car, as these are less likely to have been messed with), then sit down, read Cliff's book cover to cover before you ever get the tools out, study the parts you don't understand until you DO understand, then go through the carb yourself. I bet you'll be fine.