I cleaned the EGR tube the other day and was looking at better way to really clean it thoroughly so I don't need to do so frequently. I noticed there is a hex bolt just below the EGR which seems to plug the end of the EGR tube. I figured I could remove this to gain better access to the tube, but it's stuck. Initially, I was able to move it just a bit but now it's stuck. I've tried when it's been cold and hot to no avail. Any ideas? Is this a reverse threaded bolt?

Any help is appreciated.

For those who wonder why I would need to do this, I talked to an Isuzu mechanic when waiting for an IMG replacement and he said they use some a wire or coat hanger to stick through the butterfly valve and ream out the EGR tube. Then spray the throttle body cleaner and finish with compressed air. I have done this and it seems to work fairly well but I think that it work better if I had access to the tube from the EGR side.