Looking for ways to generate alot of 3-4 word search terms?

I am looking to find niche’s, verticals to generate 3-4 word search terms per category.
I only want 3 or 4 word terms tho. Best keyword resource for generating this data? I have accounts everywhere just need to know a good method.
OR
Anyone have any suggestions on what to use or a method to weed out 2-3 word terms from a source? Even a simple excel formula to remove 2-3 word phrases from a column.

See original post by AdManageBrett