Check the regulator. I had a persistent ng gas smell from the range - they claimed I had no leak. I only called em out once- and it wasn't that bad -1 hour service call
so I went after it myself - found an almost invisible hairline crack in factory regulator - manufacturing defect looked like, new reg., self installed, fixed it.
That was a good catch. If it's not a connection on the main line coming in, one of the most common leaks I have found would be on the gas tube to the oven main burner at the nut on top of the oven control. A gas range being what it is though, There are a number of places it could be.
