
I agree with Alan, it's probably the shaft, not the iron.
The CT's are a game improvement club whereas the 845's were designed for the better player. The lofts may be stronger on the 845's by as much as 2 or 3 degrees per club.
Stick with the Mizuno's, they are far better and your game will benefit from them more as you will find the centre of the clubface more often than the 845's.
I change of shaft may help keep the ball lower, but not add distance.
You could try adding a bit of weight to increase the swing speed at impact, but then again, why bother, just club up and swing easy, you'll hit it better all the time.
You don't really need to hit an 8 iron 150yds, you have 14 clubs in the bag - use them all, no atter what distance you are hitting each iron.
Have 14 favourites in your bag - it helps!