We just bought a new gas oven to replace failing unit and it is pretty awesome, except for the fact that we can't bake and cook on the range at the same time. If the oven is on, the range will light but only about a third of the normal flame.
I did have to convert it to propane, pretty sure I did that right, and the valves are completely open. I reused the existing copper line with a new flexible connector. Is it possible this new unit uses more gas than the old one and our lines can't flow sufficient gas?