The CE light came on with code 5. I clean the EGR valve and tested it to make sure it works when vacuum is applied and it does. The code always returns after a few cycles. I cleaned the passages as best as I can using brake cleaner and speedo cable.

The only thing I can't figure out is when is there suppose to be vacuum at the EGR valve?

How long does it keep the EGR valve open?

What is basic sequence of EGR operation?