Following in from the intermittent cough which I was getting, I cleaned out the EGR valve the other day.
It was a bit mucky.....
After I'd cleaned all the clag out of it, the solenoid seemed to be operating okay. I also gave the opening to the manifold a good scrape out. there was loads of 'orrible sticky gunge in there too!
Since then, no misfire!
I was going to completely strip the solenoid out of the EGR but it seemed to be operating smoothly so on the basis of "if it ain't broke...."
Dunno if it was connected or what but happier now.