The channel your router is transmitting at may cause some fluctuation if it is being overlapped by another router or wifi device. For something like that to happen though you would have to be pretty close to it (like a few feet). You can easily check that by using software (like network stumbler). But you would need to change channel often because most routers change channel (when set to auto) each time they restart.
Before you make your new router selection, check this out:http://www.smallnetbuilder.com/lanwan/router-charts/view
It should be helpful!