You are seeing an example of “z-fighting”, in which the graphics system is struggling to decide which of multiple objects should be in front of the other from the current point of view. The giveaway is that the effect flashes and shifts as you orbit the model because the graphics keeps changing its mind. As @colin observed, this is happening because you are working in parallel projection and the camera has gotten to be far away from the model. Having the camera so far away aggravates z-fighting because distances from camera to model are almost the same.
This camera positioning issue is a well-known problem with parallel projection, and is why the experts all recommend that you model in perspective projection and only change to parallel for final orthographic views if needed in your presentation documentation.
On other issues I noticed, you have a lot of reversed faces in the model that you should correct. Set monochrome mode so that textures don’t mask the situation and look for blue-gray faces that are exposed (I set a bright green for the back face color in the style to make reversed faces jump out).
You are also not using tags (formerly called layers) appropriately. All edges and faces should be untagged. Tags should be applied only to entire groups or components. Edges and faces inside a group or component don’t need tags because the whole group’s tag will control their visibility, and edges and faces in a single context (model, group, or component) will stick to each other and intersect regardless of what tag they use.