Query: "thoo"

[P2052 at AOL.COM]

Likewise, threw is pronounced [thoo] and throw, [thow].  Maybe this
r-lessness occurs only/primarily with one-syllable words followed by mid or
high vowels (The same speakers who delete it in throw and threw/through or
even throat [thote] never seem to delete it in threaten or threat or thrill
or three. I might be off base since I missed the initial inquiry, but, based
on speakers I come into contact with often, when it comes to initial
consonant clusters ending in "r", when r can be deleted without losing the
sense of the word itself, that deletion occurs, as in the examples above;
when it can't be, "necessary" substitutions are made [usually with w or k],
as with shrimp [shwimp] or [swimp], straw [skraw], street [skreet], straight
[skrate], strength [skrin{f}], etc.  P-A-T