Try dosing a little less. Start with 1 scoop, even a little less. I experienced the same thing when I started using Jack3d. It has to do with the synergy of the ingredients used.
The Shizandrol A in Jack3d has a profound effect in increasing dopamine and more importantly(in this case), epinephrine in the brain. This causes your adrenal glands to start pumping out adrenaline. This also causes an increase in activity in the acetylcholine neurotransmitters in the brain, which are responsible for contraction of muscle fiber. Adrenaline is your body's natural response to short-term stress or emergency situations. That, and the geranium and Theophylline to create a nice 1,2 punch caffeine-like boost. When your body starts pumping out that much adrenaline, jacking up your heart rate and prepares itself without activity, your body starts dramatically lowering your blood pressure and attempting to lower your heart rate in an attempt to maintain homeostasis. Think of it like eating a ton of sugar, being on a sugar rush, then crashing hard and wanting to sleep.
Just my opinion, try dosing less and/or shortening the time between when you actually take Jack3d and lifting. with some fine tuning, you'll find a medium that works best for you.