the problem is most likely with the TBS. I would take off the spacer and see how it performs... I bought one, installed it, had the sound you described and saw no added reason to keep, so I returned it...
I have seen many write ups about these not being good additions, make your own judgements though.
I can't remember everywhere I saw them, but go to http://www.speedtweaks.net
and click on "tips and tricks" and then on Throttle body spacers... They say it isn't good!
Black 2001 TJ, 4.0L, 5sp.
Mods: Rubicon Express 3.5" Superflex, Adj. Front Trackbar, [URL=http://jeephorizons.com/phpbb/viewtopic.php?t=786]Rusty's Steering upgrade[/URL], OME LTs, steering skid, JKS discos, and probably more :)
On order (thanks Uncle Sam): Jeeperman Rear Bumper/Tire Carrier, Upper Adj. CAs (front/rear), rear Adj. Track Bar, Oil pan skid, new steering skid, BPEs
[URL=http://jeephorizons.com/phpbb/viewtopic.php?t=645]My Jeep Pics[/URL]