Phone won't keep EV-DO data session active

I have an HTC Titan, and for some reason it won't keep a data session active, even with the always-on data hack. The primary problem with this is that for some reason, wireless sync won't initiate a data connection, which is how I get my email. I can force it by starting IE and going to a web site, which will start the data, then opening wireless sync and then performing a sync. The data session only lasts a moment though then closes. Any idea what might be causing this?