It may take a long deliberate effort to adjust your habits so that you can play well with that heavier racquet. It's absolutely a recipe for frustration, at least right out of the gate, but you may find your way to some stronger technique along the way. No guarantees, but I agree with some of our pals that it sounds as though that Dunlop isn't letting you get away with arming the ball quite so much.
You may need to limit your work with that heavier Dunlop to the practice courts until your timing changes. I've tried this with 13.4 oz. LM Prestige mids (leaded up) that I used as "trainers" to adopt a better kinetic chain with my strokes. At first, they exhausted my arm (especially my shoulder) after about 20 minutes on the grinder, but my persistence paid off after several weeks and I learned to make those heavier racquets work.
The idea I like to suggest here is to focus on your legs and your feet. You might need to get hyperactive with your preparation and learn to burst out of your split-step toward your ready position. The idea is to always be ready ahead of the ball, not just on time with it. Instead of your stroke execution going like: 5-4-3-2-1-swing, you need to set up early enough to be able to swing that heavier racquet at 5-4-3-swing. You'll destroy the ball just fine as long as you don't delay the initiation of your swing. Rush your setup!
When you're doing this right, you'll get tired legs instead of a tired arm when using that Dunlop - or any racquet! The heavier frame will push you to drive your strokes with those big muscles in your legs and core.
Not saying that you have to use that heavier Dunlop - just offering a plan of attack if you decide to keep at it. If a racquet is just too heavy and frustrating, better to lighten up a little and use what you can live with out there. I like a hefty frame, but it also needs to be "light enough" for me to play with every day. If your Dunlop is sluggish, you may also like it with some lead under your grip for a little more HL balance. Maybe not, but it's a cheap experiment that might help.