it could be the radio since 3.42.30 is ported from the vogue(touch). i would try 3.42.02 again and see if there is any improvement.
some people said that 3.42.30 caused them to lose signal strength and slower gps depending on the carrier.
so try 3.42.02 and maybe that will fix it.
here is the link to that thread i was talking about
http://forum.xda-developers.com/showthread.php?t=406297