@geo-milano
This might not be a hardware problem. Did u install something from Cydia (or installer) to modify the vibration pattern? This could be a corrupted SystemSoundVibrationPatterns.plist in the Celestial.framework. Try replacing the plist file with the stock ones and see how it goes. If you restored the phone but sync the old setting then that should answer the question why it still persist even after restore. Syncing with old preferences/backup will copy the old (corrupted) settings (plist files) back to the phone.

Aiyaaa ... one more post. Break vows again.