If the gas output on your gas range is just too high for delicate cooking, the solution could be a heat diffuser. That's a metal plate that sits on top of the burner, absorbing and diffusing heat to create a gentle cooking surface. Both germanpotatosoup and jhamiltonwa gave high marks on Chowhound to the SimmerMat, a steel-plate heat diffuser from a company in New Zealand. It's great for cooking oats, with no burnt crust to clean. John Francis got a heat diffuser with no brand name from a hardware store and finds it works great to achieve a true simmer, rather than a low boil. Turns out kseiverd uses a cast iron griddle for heat diffusion, reporting it works very well to barely simmer a sauce or soup, or just keep them warm.
Discuss: Heat Diffusers?
Photo from problemsolvers.com