Hearing how people define simple terms like 'liberal' and 'conservative' speaks volumes of how and why they think.
To me, economics can be distilled down to how high the tax rate is and how many services the government provides. This, of course, runs the gamut from the most theoretically 'conservative' simple societies where there are no taxes and no services to what are perhaps the most 'liberal' modern societies like Sweden where taxation is extremely high, and the government provides a permanent welfare state. Realistically in the US, a fiscal conservative supports low tax rates and a government that does not provide many services.
Social issues need not be economically relevant. Teaching intelligent design, gay marriage, drug legalization, and abortion are not necessarily tied to money. Some social issues are very economically relevant, like defining the minimally humane provisions for keeping a person alive. It's a pointless exercise if you consider only economically relevant social issues, because as has been stated, you can't be fiscally conservative and socially liberal if your idea of social liberalism requires fiscal liberalism as well.
Most of my friends voiced a belief that our country as it is now is too economically liberal and too socially conservative. That is, taxation rates are too high, the government provides too much, and they think it is unfortunate that gay marriage is mostly illegal, that drugs are mostly illegal, that access to abortions is too frequently threatened, that moves to push religion (in the form of intelligent design) into the public sphere too common and too forceful.
So, to me a fiscally conservative, socially liberal politician would move to decrease tax rates, cut government spending across the board (from the military to corporate subsidies to the welfare system), legalize drugs (especially marijuana), work to preserve abortion access and keep intelligent design out of public schools. Neither party embraces this platform, hence the need for someone with these beliefs to run as a third party candidate.