Alright, I will try weighing form now on but...most of my stuff has only given me measurements. Should I just then get a scale and go off of a cup is 8 oz so if I need 3/4 a cup weight to 6 oz? Also heat may have been an issue, I came home one day to our air conditioning being off and the whole house being 81 degrees.
A cup of sugar is around 6 oz. (actually 4.5-6.5 probably, depending on size, of granule, humidity etc.)
I would guess that part of the problem is a but too much sugar (overcarbed problem) but the lack of head retention... you say it's like pepsi? so it pours and foam forms but then immediately falls back leaving no foam? When in the ferment process did it get up into the 80s? if that happened in the first three days or so it could well have caused fuesels to form which can wreak havoc on head retention. There are a range of infections that could account both for the lack of head and the higher than expected carbonation as well.
A couple of things to try next time:
1) Skip the secondary, not needed, just an additional opportunity for something to get messed up.
2) skip the dark DME and make up for the color with some more dark malts and some dark crystal in the steeping grains
3)watch that ferm temp, particularly in the early (first 3-4) days of fermentation.
4) weigh instead of measure the priming sugar
5) think about using a no-rinse sanitizer. When you rinse sanitary vessels with un-sanitized water you risk undoing your sanitation.