my combo is VERY simmilar to yours.. maybe i can help at least a little. i'm using 42's and no btm or fmu.. i have a chip tuned for it but it runs better sometimes by just retarding the timing. (depends on the weather)
first.. check to make sure there are NO leaks between the mass air and TB ... next make sure the bypass is not backwards...
try ngk b9es plugs.. or autolite 23's...
a lot of time the btm will give ya trouble so try unhookign it and just retard your timing.. you will have to idle it up some but it should be ok..
e-mail
bar5516@aol.com if u wanna talk about it some more.. i've been through just what u have so i might can help.