Suburban SW6 lights but drops out after 30+ seconds

So the flame goes out first and 5 secs later the 12v stops at the gas valve and it also shuts the gas off? The time it stays burning after first getting lit varies, and sometimes it relights and then quits again. You wait and it will fire up then quit again.

So something is getting too hot quickly and then it works again when it cools down some?

After the flame goes out it takes 5 secs for the gas to shut off, so the flame sensor system is working properly?

What does the flame look like when it is burning?