Yes, the stimulus plan addresses underlying economic problems, because the stimulus carries with it new laws and regulations that address underlying problems. The sub-prime mortgage crisis needs to be corrected, and Bush's plan takes this into account by creating new regulations for the industry. The stimulus plan is a thoughtful plan, which kick starts the economy while also taking into account the important underlying issues, and creating a plan to correct them.
The supposed economic stimulus plan proposed and ultimately enacted by the Bush administration did not address the underlying flaws in the American economy. Stimulus does not address the problem of over regulation preventing new business from forming and preventing small businesses from growing. Instead, it provides a temporary handout that doesn't fundamentally change the economy.