I have a 99 nissan maxima gle that cuts off while driving. I have replace camshaft, crankshaft, and master air flow sensors. I have had my ecm unit tested and still no avail, if anyone has any knowledge to what I can do, please help.

Replacing the coil module, which sometimes has an igniter chip inside, could very well solve your problem. Here's what it looks like and costs:

http://www.partsamerica.com/ProductList.aspx?PartType=190&PTSet=A&SearchFor=Coil

Your is situation is quite complicated. I tried replacing nissan body parts (www.car-stuff.com/nissanbodyparts.htm) one part at a time and I can say some were not that successful. :o I suggest that you bring it to a trusted local mechanic. :p