P0401 EGR Flow Insuficent. Already cleaned EGR not sure how to trouble shoot next?
 

My 2 wheel drive 97 Blazer 4.3 has a check engine light. When I pulled the code it was P0401 EGR Insufficient Flow so I pulled the EGR off and cleaned it. It wasn't very dirty to begin with but I cleaned and checked the valve and it seems fine. I also did my best to clean the ports where the EGR connects with a steel wire on a drill and carb cleaner and then replaced the filter. Light is still on and I am unsure what to do next and registration / smog is due and a check engine light is automatic fail.

Could it be the sensor on the EGR valve? Or would that be a different code.
I am unsure what to do next. Any help would be greatly appreciated.

Flow codes are typically clogged up ports. May want to keep trying cleaning the ports. The old 3.1 and 3.4 motors were notorious for this. We would sometimes use a coat hanger to get through the ports and other times we would have to remove the upper plenum. There is a flexible tool made for this exact problem that has a bit on the end that cuts through the carbon while working through the ports.

Thanks for the reply.

how difficult is it to remove the upper plenum on the 4.3 to clean or is there an easier way?

I tried coat hanger and wire on drill through egr port a few times but the code isn’t clearing. Curious if there is another way I might try if removing the plenum to clean is a big job.