spark plugs definately. You lose a lot of power with old worn spark plugs. They are so cheap $2 each X 4 and easy to replace. Correct tire inflation is major.

So, George Bush is making a lot of money lately considering how most of his family and Cheney's are invested in Exxon Mobile and oil industry. Maybe your friend Karina Lau died for tycoon profits then huh? very disheartening