Adderall and an ECA stack, geez bro you must be flying around. I am prescribed adderall also, and I can tell you that depending on when you take it you will see a pretty good jump in your RHR and HR during exercise. Also, when trying to find your Target Heart Rate it would be more accurate to figure in your Resting Heart Rate. For instance if my RHR was 60 bpm the formula would look like this......

220-24 (Age) = 196
196-60 (RHR) = 136
136 x .70 (Intensity) = 95.2 + 60 (RHR) = 155.2 bpm

If I follwed the method you used my THR would be:

220-24 = 196
196 x = 137.2 bpm

Pretty big difference! The better cardiovascular shape you are in, the lower your RHR should be.

I usually do cardio after I lift, but I take 24 g Whey/10g BCAAs 10 mins prior to finishing my lifting. I then do 30 mins of cardio at 60 -70% of my max, after I am finished I usually wait around 20-30 mins and then have my regular PWO shake.