Kept getting this code. Truck has 331k but engine replaced 9k ago with a low mileage engine from a 96 or 97. Would have to check receipts from father in law who owned it since 1998. EGR looked ok and held vacuum, modulator was new. I assumed intake port was clogged. Took it apart and found this metal tube was clogged. I tried carb cleaner, brake cleaner, straight degreaser, ultrasonic cleaner, oven cleaner, compressed air, but wouldn’t come clean. Finally I clamped it to a gate outside and fired up the gas pressure washer with the 15 degree tip. Didn’t clear it out after a few blasts so I swapped for the 0 degree tip. About 5 seconds of that and water started spraying out the other side. It worked! Didn’t have to buy a new EGR valve. No more CEL and it does seem to run better but I don’t know if that’s the EGR system finally working or blasting carb cleaner through all the ports I could while the valve and all the hoses were off. I had also cleaned the EGR temp sensor with a wire brush. It was coated in deposits but cleaned up nice.
