DarthFerret said:
Congress in 2000 (republican)
Congress in 2008 (democratic)
Congress in 2001 - 2007 (Republican)
Congress in 2007 - 2008 (Democrat)
Which one had more influence on the last 8 years?
And to answer your questions, yes, one man does have a lot of power in our government, despite our system of checks and balances. It's actually quite easy for an administration to mislead Congress, since they control a lot of information that is dependent on decisions being made (see Iraq war).
However, that is hardly what's happened the past 8 years. Most of the Bush administration was run with a blank check. Since there's only two parties in our current political system, there are only checks and balances when the parties split control of the executive and legislative branches. Since Bush was in office mostly with a Republican congress, he could basically do whatever he wanted for 6 years.
But even that has nothing to do with gas prices. The high gas prices are almost completely the fault of China. As a developing nation with a very high population, gasoline is in very high demand in China and the world can't produce enough to keep up. It has little to do with the oil companies and even less to do with the government. It's basic supply and demand.