Pakistan hates the United States. You can spend hours arguing that they don't but the simple fact is, they put on a smiley face and take America's money, but deep down inside they hate all westerners. I'm not even going to go into depth about how short a distance Osama Bin Laden was living from a Pakistani military base, or the Al-Qaeda members of their government, but the US should only give money to it's friends, and Pakistan is yet to prove itself as a friend, instead of a Flag burning, Christ-hating terrorist state that hates America with a passion.
The United States shouldn't just suspend all assistance to Pakistan, but it should recall all foreign aid in an effort to protect its own citizens first. There are plenty of hungry and homeless people in the United States that need help before Pakistan's own citizens. The Pakistani government may have provided a haven for Osama bin Laden after 9/11. That alone is enough to suspend aid.
Diplomacy means we need to keep up some sort of relationship with countries such as Pakistan. However, there may certainly be conditions imposed, as with any other nation. We need to revise our assistance programs so that we are giving the right amount and type of aid and seeing if these nations are truly allies.