I think the WIFI is a radio like the BT and the phone. If it is a software problem, then your driver for the tiacxwln1 adapter may be bad. IDK if you can get that separate from the radio ROM. But since you have flashed so many radios and ROMs, it should have fixed itself by now. I think hardware. If you can spare the miniSD slot there is an adapter that fits:
http://msmobiles.com/news.php/5108.html
That's my 2 cents.