Clogged Plenum EGR passage

Hi guys,

I recently discovered that my 2000 GP with 145+ km has a clogged EGR passage in the upper plenum. After doing some research, I learned that these GM 3.1L/3.4L engines are notorious for having problems with a clogged EGR passage in the intake manifold; resulting in a P0401 trouble code. Is this causing my poor acceleration?

What is the procedure for cleaning the passage hole?
What are some of the symptoms of this problem?
What are some preventative tips I can take?

Thanks!