Hi,
As far as the vacuum, it is controlled by an electronic vacuum regulator valve. So vacuum changes based on conditions. It will fully actuate the EGR once the vehicle is warm, under a moderate load, and the PCM determines it can open
The thing is this. If there is no power, it sounds like the EGR is open at all times. We need a vacuum for it to open, so let's try something.
I attached a pic of the EGR vacuum regulator below. Allow that to remain connected, but I want you to remove the vacuum supply at the EGR itself. At the end of the vacuum hose you disconnected, plug it with a screw or something that will prevent vacuum loss.
Test drive it and see if it runs any differently. If it does, the regulator may be faulty
Let me know what you find.
Joe
See pic below.
Monday, January 30th, 2023 AT 3:34 PM