After having gone through every coax connection in my rig; I agree the coax terminations would be a good place to start. The ones I took apart obviously weren't done by a skilled worker, to be kind. You do get signal loss with splitters and all splitters aren't created equal. Mine came supposedly wired for satellite on 3 different TVs (I have one outside) and none of them worked. Raw signal from the satellite dish to receiver is very high frequency and all components in the system should be rated for (if I remember right) 2.0 or 2.5 MHz or higher.
There's always the option of adding an amplifier, maybe a distribution amplifier at the point the antenna signal comes in (likely bedroom in a front bedroom model) with multiple outputs. send one output to the bedroom and find the coax feeding the living room and attach to the other output. I've used these guys in the past and they actually have knowledgeable people to talk with over the phone and have very pleased with their recommendations:
www.solidsignal.com