Glad to have more people moving to Pittsburgh from out of state!
In addition to sales, I'm a rental agent with Coldwell Banker in Pittsburgh, and our property management division is also able to help locate rental homes for you. As you've found, it can be a frustrating search online, because there's often not much that comes on and when it does, it often goes off quickly. I'd be happy to help you in your search, and know there are at least a few options in Mount Lebanon right now. Feel free to contact me at firstname.lastname@example.org and we can discuss your other needs and price range.
you can also visit our page below, an easy and convenient way to search for rentals (or homes for sale) in areas of your choice.