Web responses from servers behind LTM4000 being truncated

I'm fairly stumped by this issue. We have a small webfarm behind a pair of HA LTM4000's running 11.2.1. Most requests go through the F5's just fine. However server responses that are returned and are greater than about 5 or 6K get chopped. The response ends and the client just hangs with a partial response. I've tested this rather thoroughly. I created a very length html file (200K in size). From another server on the same subnet, the file transfers without issue. Doing a curl request on the inside interface on the F5 transfers the file without issue. Transferring the file from anywhere in front of the F5 causes it to be truncated. I've checked and double checked everything. It's a standard http VIP, nothing special about the pool, no iRules, nothing. Anyone have any thoughts about what might be going on? This is killing us.