I have free memory of about 24 mb left . When i install apps as small as 1 MB it says insufficient memory. I tried many times but the problem persists. I have rooted my mobile too.
Go to Settings>Apps>All and uninstall Google Play Store. This will uninstall only updates of new version, and replace it with the old version. Then you can download without the "Insufficient Storage ERROR".
insufficient-memorytag