Re: Pickit3 Connection Failed
Could you try the latest version of MPLABX v4.05, I tried the same with Pickit3 and 16F886 with power target from tool. It works fine.
Note: If you still feel the issue persist, then go to IPE >> Setting >> UnCheck Auto Firmware and Select Manual Firmware.
Point your old PK3 firmware file from your old MPLABX.