If syntax highlighting works, does the word "config" highlight as a keyword (by default blue). If not, check Tools > Options > Text Editor > File Extension, and make sure you do not have .uc files set to open in the Microsoft Visual C++ editor.
Do you have the Reference Source path configured, where the reference sources show in the Solution Explorer?
Do errors show in the Errors window when you have UnrealScript files open? Certain errors cause IntelliSense to fail, in which case you should send me one of the failing files so I can fix it.
Let me know!