My dad had a '00 with an NV4500, it did the same thing. I checked it with a scanner and it ended up being a Crank Position Sensor. I think it was a little pricey, but its better than a pump. Autozone I think lets you use their code scanner?

 

With a scanner you can read APPS voltage and see if there is a flat spot or dead spot. From there you can remove the APPS and run an Ohm meter accross a couple of pins to see if the APPS is the cause. I don't remember right off hand which pins, I will have to look it up.