There is a difference between antenna amplifiers and distribution amplifiers, so make sure you use them appropriately. Less Is More Believe it or not, having the maximum amount of signal isn't always the most desirable thing. When combining sources, sometimes the strongest one must be attenuated to minimize interference with weaker ones. When I added the modulators to the existing home cable mix, they worked fine, but the channel 4 satellite receiver picture suddenly developed interference lines in it. By unplugging one modulator at a time, I isolated the offending unit.
Attenuators can also help problems caused by amplification.
If you think some problems were caused by adding the amp, try adding a small attenuator to the input, the output, or both. This hardens the amp against any impedance variations. A terminator is nothing more than an F connector for RG-59 coax with a 75 ohm resistor soldered in the sleeve, the free end serving as the center pin of the connector. You can buy them premade, or even make them yourself. The Terminator Unterminated splitter ports can cause reflections on the coax.