The problem is that with a splitter you are losing some signal strength when you split the signal. Instead of a standard splitter I use this at my place:
http://www.amazon.com/4-Way-10dB-Vid.../dp/B000LY25FI
I use all 4 outlets and it works great however I don't use a preamp. My antenna runs about 15 feet to the amp and from the amp my longest run is around 75 feet. It's less than $18 I would try it and if you get no improvement return it.