I've been having issues with the Play Store's recent 4.9.13 update on my Blu Dash 4.5. Every time I try to install or update any app that is more than 1 MB, I keep getting an "insufficient storage" error, even though I have about 120MB on the apps partition free. Apps do install and update on an older version, however. In addition, the icons on the Play Store have weird black borders. I have searched all over the internet and I have yet to find a solution for either of these problems. Apparently, most devices affected by these bugs are using MediaTek chipsets and have Android 4.2 on them. My phone is using the stock ROM and is not rooted.
uninstall updates
which is located on Settings>Apps><Swipe over to>ALL and select the Play Store. See if reverting back helps. And if so I'd say there is a pretty bad bug within that version.