I've made several new placeables mainly from ripping them out of modules ie, statues, pillars, rocks, etc..I have been able to get them in game with their new walkmeshes and they look good. However, I do experience one little glitch with some of them..they will disappear briefly sometimes when the pc is moving past them or if they are leaving the angle view. Then if I go back or move the angle of view they reappear. Any thoughts on how to correct this?

If they are large items I don't believe it can be. I ran into the same issue when I made the Ebon Hawk into a placeable at certain angles the Hawk becomes invisible.

I think this is something hardcoded into the game engine. Once the camera doesn't face the object it dissapears, not being rendered. As well from a certain angle/ amount of degrees off, they go up in smoke.

I've encountered this as well, so far I think there isn't something we can do about it.

A feature most likely build in, to save fps, to ensure a decent flow of the game.
Keep in mind K1 and TSL are becoming "ancient" in game terms. So it was an acceptable trick back then.
Infact many games today still have these sorts of tricks. NWN2 for example has 3 models for most objects.

Low poly for distant views; a medium model and then a high detail model once the player gets close.
Again this is all to keep the game go fluently. It's quiete understandable. No need to render polyies you won't see.

They can be used on other places :p

Thing is Placeables are used for smaller, mostly inter active objects in the game. So this vanishing feature isn't that obvious. Of course it becomes if you use large models.

I think the largest placeables in the game, are the land-speeders.