well offhand i don't see how what you posted for the plane has anything to do with the drawtext? Nor do I see any issues with the drawtext other than the fact that you are basically drawing them on top of each other and over the top of the Stats... I placed both snippets in a program and have not had any issues. So I can only guess that maybe there is another issue inside your program that is causing this. Without an example though, we can only guess.
On another note, you may want to actually space out your text so they are not writing over the top of each other and the stats...
Local Vec:TVec3 = Vec3(10, 10, 10)
Local text:String = "camera"
DrawText(text + vec.x + vec.z, 0, 100)
DrawText(text + vec.x + vec.z, 0, 120)
DrawText(text + vec.x, 0, 140)
DrawText(text + vec.z, 0, 160)