Why am I be hooking irons with regular flex, need help

Hi all, I'm in a bit of a odd situation lately and request some help to resolve it.  I've been using Taylor Made 320 irons with S90 rifle shafts for about ten years now and absolutely love them.  I recently started reading internet content and found out that I may be using the wrong stiffness of shaft.  I've been told I have a smooth swing and I hit my 5 iron about 150 yards so I bought a used set of regular shaft 320's for a good price.  Additionally, I also bought a Tour Preferred CB 6i and also RBZ Max 6 iron both in regular graphite shaft.  I've hit with all clubs with regular shafts and haven't been able to get any distance on the clubs (now it seems I'm hitting the six iron 125 yards or about twenty yards shorter than my normal swing), additionally, I have also established a nasty hook on most of the shots I've taken.  Normally, I hit my irons dead staight with very accurate shots and now I can't do anything.  I don't want to abandon the regular shafts yet but I'm really confused as to why the clubs would hook instead of slice, as I would have expected if they were too flexible for me.  I've sold my old set in stiff flex so I'm in a little bit of a bind right now but I'm hoping that there's something that I'm not thinking about for this problem.  I was thinking of trying the CB's or RBZ max in stiff but would prefer to figure out this current problem.  I'm hoping it could be in my mechanics but I haven't changed my swing any since buying the new clubs.  One more thing I haven't talked about, I'm overseas and probably won't be able to get a professional fit right now so that's not in my thinking at the moment.  When I return home, this will be an option.  Any help would be appreciated.  Thanks

Too "flexible" would be hook prone and too stiff would be push prone. Having stated that, I am not a certified instructor so my advice on swing mechanics may or may not be exact. My thought is your lower body is not leading the swing toward the target. Instead your lower body is stopping (no weight transfer to your front side) and your hands are "flipping" through the shot creating two separate shot patterns; either a hooded hook or an open faced cut. Whenever I have these problems it usually was created by trying to over hit/swing. My way of correcting this is to go to the range and hit a pw and seven iron with a half swing and feet close together. My focus is fundamental and tempo driven with no concern for distance. That is what works for me and may not be your best approach, but you may want to give it a try. Its always best to have a knowledgeable person exam your swing. in person, but video seems to be a widely accepted alternative.

As far as shaft advice I am GCA certified and spent several years as the head clubmaker at a local Golfsmith. However, the most accurate shaft advice is done in person by knowledgeable people.  Im not a fan of Dicks or GG or other such places, but there appears to be some highly qualified members of this board who could profile your shaft needs. Hopefully one lives in your area.

Thanks a lot for the help, I really appreciate it.  I'll have to give feet together technique a try and see what happens.  I'm also really looking forward to having somebody analyze my swing to determine what is going on with it.  I'm going to try to get to the range this week so thanks again.

When I was in high school and early college, I played R-flex irons. Then, I went into the military and put on about 20 pounds, and got into pretty good shape.

I started hooking the ball on my misses. So, I switched to stiff shafts, and my hook problems were solved.

Fast-forward ahead 30+ years, and I'm suddenly losing distance and starting to leave the ball out to the right. Solution: move back to Regular shafts.

As waldo suggested, have someone check out your swing, and then get a fitting.