I may just need to open a bug with intelliji but I find the behavior so peculiar that I thought i'd ask if anyone who codes go in intelliji may know what's going on.
I uninstalled go 1.9.3 and installed go 1.10. After I do that, intelliji can no longer find any packages in the std lib and autocomplete no longer works. third party packages its fine with. I reinstalled 1.9.3 and then intelliji can find the std lib again. Since I haven't upgraded intelliji, I am guessing something changed in 1.10 that's breaking intelliji's ability to access the std lib but I am at a loss as to how that could be.
I did verify that go 1.10 install is working (e.g go version go build go install all work etc)