I am sorry for your issue.
I have the same adapter with latest driver connected to the local AP at 802.11n (104Mbps) with several overlapping networks, and no packet loss after a <ping –t> test the AP. At the same time, few other adapters are connected to this Intel® wireless adapter via Intel® My WiFi Dashboard, one of them is a smartphone which does not experience packet loss either.
It might be something specific between this adapter model and the other ones you are using or something else; however, it is a bit difficult to test with those other adapter models at this time. Configuration of Intel® My WiFi Dashboard is limited but in general we offer some recommendations for 802.11n connectivity:
Intel� PROSet/Wireless Software; Intel� PROSet/ Wireless Software Downloads
Wireless Networking; How do I improve my 802.11n wireless performance?