Can you describe 'Not Steady' in a bit more detail? Perforated stainless steel sounds a bit hit and miss, you need a free and uninterrupted flow of gas evenly distributed across the burner face for a good combustion.
As Andy says check the basics first such as jets are clear, gas cooling effect is not playing a part etc..
Edited By Richard Simpson on 15/12/2018 10:50:18