Experiencing excess saliva recently. history of mild tingling/numbness/arm weakness/need for deep breath. normal blood tests/ekg/brain mri. anxiety?

It depends.: I do not think that a heart condition is likely, given your age and results under normal conditions. It depends on when you get these episodes, and under what circumstances. If they happen during a hectic period in your day, like at work, etc., i would say anxiety is likely. However, if they occur at random points during your day, or after exertion, i would say get a stress test, etc..

Could be: Anxiety is a plausible explanation. There are so many other possibilities that are beyond the scope of this forum.. Best bet is to continue searching for a cause. These symptoms are also consistent with a neuromuscular bite problem. A bad bite can stimulate the hpa (hypothalamic pituitary adrenal) axis (selye) as well as alter cervical vertebral, position and compress axiallary nerves.