Have you tried a bitter apple spray? Its a terrible tasting spray that you can put on the things he should not be eating. It probably couldn't be used on fabrincs, might stain, but its could for like electrical wires, or wood moldings.
Also, if he is chewing on fabric things, or fuzzy things, try not to give him toys of the same consistancy. He might not be able to tell the difference bewteen his toy and the thing he should'nt chew (your slippers, or couch).
Too many toys can also be bad. Limit his toys to 2-3. This will also help give your pup a sense of what belongs to him, and what doesn't.
When he is chewing on something bad, don't just shove a good toy in his face. Make him "work" for the toy, by chasing it. If you just hand him the toy, he may think he is being rewarded for chewing the "bad item".
Hope these tricks work! Good Luck!