Add a 3" riser board above the cabinets and under the molding? Mount the microwave a little higher? Making the duct turn into the wall will restrict airflow and add noise - though my previous ORMs were so noisy I don't think ductwork could've added to the din.

Thanks for your reply and suggestions But I am so short 5'1" I really hate to raise microwave up...it will be hard enough at the 18" from the range....

"Making the duct turn into the wall will restrict airflow and add noise"

I sure don't want that to happen...
Wondering "IF" it will be better to just Vent it straight up thru the ceiling.....Again I really don't want to do that because of having to come up with something to Hide the 3" of vent that will show...
Anyone have any ideas?