Generally speaking, anything inbound to FLL from IAH goes back to IAH and anything inbound from EWR goes back to EWR. I've never seen a swap where a EWR arrival turns for IAH or vice versa. OTOH, anything sitting overnight might be subject to re-assignment depending on that ship's upcoming schedule.

The flight times are spaced enough apart that it's reasonable to assume that an inbound flight will turn outbound about an hour after arrival.

If in doubt - pda.continental.com/info is your friend