This is a game I just played as white in the Poisoned Pawn variation of the Najdorf Sicilian with a time control of Game/7 with 4 second increment. Once out of my opening book, I floundered a bit for a plan, and soon I found myself lost. I am wondering where exactly I went wrong and for any improvements which I should have made. Any help is appreciated.

Bg5 was a weak move leaving queenside completely exposed.  Like you also said, letting those three pieces hang was another mistake.

I play it differently so cannot help a whole lot, but I do wonder if you are truly in "book" through move 18.  Are you?  I find it a fascinating position and am sentimentally on your side as I have often claimed taking the b pawn with the queen early in the game is universally suicidal.  I believe I usually play Bd2 and not g5.  But it may well be playable.

starr, Bg5 is a very well-known and developed move for white and is perfectly fine. Also, the three pieces appear hanging, but they are all held at least after a move like Nce2. I believe that my attacking chances give me compensation there, and like I said, the first 19 moves are all book.

I worded that badly, I realize Bg5 is book, but I am unfamiliar with it.  I sort of question other moves in your Bg5 variation, but if they are book and have stood the test of time, i will look for other later possibilities.

I looked into this and 19 Rf4 seems to be what is played in every variation I found.  It seems dangerous, and only sometimes works in the games I played through.  It is indeed fascinating.  I like the following site.  It is a bit awkward and "buggy" and does not let you link to specific positions, but there are lots of games and they let you search specific positions deeper than most.

http://www.chesslive.de/