Could adult add meds historically well tolerated eventally make resting pulse high (90's)? Do people have to quit stimulant when they start aging?

It's Possible. Other things may have happened such as changes in weight, other medications, quitting or starting smoking, or just plain aging. Best to see your primary care provider about this. It could also be that your pulse is high for some other reason too.
Yes, they are speed. Most add drugs are amphetamines and can and do speed up the heart rate. I think it is always better to find and treat the real cause of the adhd symptoms rather than take speed, which is addictive, to treat the symptoms.