I've known the phrase "RTFM" for many years, and I've been using the phrase "TSOR" for about three years, but I had never previously encountered "STFW."
At first I thought it was a variant on "STFU" ("Shut The Fuck Up"), but from context that clearly wasn't right. (The context was ESR's How to Ask Questions the Smart Way, which I just saw for the first time even though it's apparently been around for years.) Then the document expanded the acronym: it stands for "Search The Fucking Web."
Sort of like TSOR, but blunter.
. . . I'm obliquely reminded to mention that a few years ago, a tech-writing group that I was in named a server "wtfm"--which, of course, stood for "Write The Fucking Manual."