You have probably received numerous responses to your post by now. But, just in
case you haven't.
The current spelling is Iasi. It can be spelled many ways. Yassy. Yassi.
My father was born in Iasi. So was my grandfather and many aunts and an uncle.
It took me awhile to locate my grandfather's Ellis island records because Iasi
was misspelled as Tassy. The J looked very much like a T. My advice is to look
at every possible spelling when looking for records.