A tune would be your best bet to get rid of a rich condition. I just went back and re-read your original post. If you are using the 96 wireing harness, the 03 MAF won't plug right in. 02 on up, they started incorporating a temp sensor in the MAF sensor. It is a six wire hookup, whereas you probably have the 4 wire plug.
A TB and plenum wouldn't necessarily lean you out. Is this the issue, running too rich? Is it because of the combo of parts you've put together?
Have you had it on a dyno to verify this rich condition?
A C&L MAF will lean you out. That's really all that a C&L MAF does.
The Pro-M MAFs are much better IMO. They don't reuse the stock electronics like the C&L does.