Do you have a flat top cooktop? Might be your problem, but more importantly you need to look at your pot and or burner. You need direct contact to maintain heat/high temp to maintain the 212 degrees F. So maybe a different type of pot.
Why is the oven and all burners on at the same time? All you need is the large burner under your brew pot.
Why not try a portable propane stove? They can be had for pretty cheap...I tried to brew on an electric stove once and I had issues keeping the temps high enough as well.