What can I do to mitigate radon while waiting for a full radon mitigation system?
Radon doesn't cause persistent coughs, and certainly doesn't cause miscarriage.  Radon is a non-reactive, radioactive gas that can increase your risk of lung cancer after being exposed to it for long periods of time (years to decades).  Reducing the radon levels in your home will do nothing to stop your cough or any other chronic health problems.

Mold on the other hand can certainly cause allergic reactions, and mold is commonly found in basements.  

Even at the radon level you're measuring the risks are relatively low.  Assuming you don't smoke, if you lived in your current home your entire life you'd have an additional 1% chance of getting lung cancer.  And that assumes you live in your current home your entire life.  Even these risks are estimated risks, not measured ones.  

If you look at the risks, a level of 4 pCi/L is the equivalent risk of dying in a car crash.  But yet nobody seriously advocates not driving.  The point being, we accept this level of risk all the time without serious issue.

http://www.epa.gov/radon/pubs/citguide.html