I generally disagree with this statement. It is purely an emissions boondoggle in these older trucks and is a potential source for maintenance issues in the future. If your vehicle is running great and has enough power it will indeed help your engine at cruise by effectively making it work like a smaller displacement motor. Most of these old trucks aren’t operated in a way that would take advantage of that benefit at all. My take on it is to wait for something on it to fail and then fix it by completely removing the EGR system. If it is working as intended and the truck is working right, then leave it as-is until it isn’t... which shouldn’t be too long as the EGR system is well known as a point of failure.
When everything is working right it isn’t a big deal except for the carbon buildup from the exhaust in the intake... when it isn’t working right, it will cause all kinds of drivability issues.
As for the issue you are having now, I would check to make sure you didn’t leave any vacuum sources open. You should be able to hear the sucking sound with it running.[/QUOTE
Don't want to start a war. But everyone on the fence regarding EGR Google the following. EGR wiki,,,, EGR and preignition,,, EGR and
https://www.motor.com/magazine-summary/driveability-corner-oct-2012/
my 1985 305 c10 runs way better with it.