1992 Other Ford Models Car won't start in cold weather

I have a 1992 Ford Topaz 2-door with around 32,000 miles on it. Car runs great except when the temperature gets right around or below 7 degrees above zero. Forget it if it is zero! New battery, spark plugs, spark plug wires, air filter etc. Then engine cranks but will not start. No mechanic I take it to can find or fix the problem. My friend told me to try ether (starting fluid) but is that really safe on cars?

Any help will greatly be appreciated as I am @ a loss to fix this problem.

Thanks,
Scott