1992 Dodge Dakota missing when you kick it down?

I have a 1992 Dodge Dakota with a 318 motor in it. Sometimes, when you go to kick it down, it'll start to really miss and spit and spatter, and wont go over 3,000 rpms because it will hesitate so bad. I have replaced the spark plugs twice, the wires, and the coil just above the power steering pump. It gets really annoying when you try to pass someone, and you have to keep the rpms below 3,000. When you kick it into 3rd gear, it'll actually slow down because it misses so bad. I was thinking it might be the fuel pump, but i dont want to spend $180 for nothing. If you have any ideas, please let me know. Thanks.