I baked two 9x2
coconut cakes during cooling both cake shrunk . when i took them out of oven both were little over pan rim few minutes later both shrunk from 2'' to about 1 1/2'' only thing i changed was from sour cream used italian custard . can some one give us a tip what went wrong?

Absolutely nothing went wrong. All cakes shrink slightly in size once they have cooled. When anything is hot, it expands, as it cools....it shrinks. If your cake ever looks "shriveled up" once it cools.....it was over baked.

With the little information you provided it is very hard to say. If we had pix it would help too.

I don't know what italian custard is but it sounds like there is much sugar in it whereas sour cream does not have any. This could have thrown off the whole recipe.
It also sounds to me like there was too much liquid in the recipe.