P0401 Insufficient EGR Flow Fix 3.1 GM

[rcvetk]

When code P0401 popped up, I pulled EGR valve and ports look very clean.
Map sensor tested good. No vacuum leaks, Pcv valve good.
Bought New EGR valve, for $110, didn't cure it, ouch!

Pulled EGR valve again and shoved piece of aircraft cable into manifold port.
Went half way in and stopped. Port was plugged, even though it looked very clean under EGR valve.

So, plugging occurs half way up port due to cooling of exhaust gas before entering intake manifold.
You have to pull throttle plate to access EGR port outlet for cleaning.
Port goes to left under EGR and comes out on right side of intake manifold inlet, about 2 inches in.

Will need stiff wires, small screw drivers, small tubular brushes, parts cleaner, to clean, it's not a straight shot across.

This was on a 1998 Monte Carlo 3.1L 95,000 miles and well maintained.

And yes I did have the infamous intake gasket problem which I repaired at earlier date.