Erratic oven behavior

Hi,
I need help with my Maytag range.
The broiler works as it should but the oven is acting erratic.
What happens is that when you start it up the igniter begins to glow but it takes a few minutes before the gas valve opens and lights up, then it is at full flame for a few seconds and then goes up and down to almost nothing and also makes a strange noise as the gas is going up and down.
Please help.
Thank You
Sumac:)