ignition coil problems

can any one tell me what would cause the ignition coil to burn up and foul the plugs in # 2& 3 cylinders after driving 10 to 12 miles in a 1997 toyota tercel

Thats not a big problem. You can fix that by inspecting if its not grounded. Maybe just replace it.

Toyota coils can fail without technically failing. They can pass the usual resistance tests yet still fail. Why? They can produce a spark, but isn't hot enough to fully ignite the air/fuel mixture. Your plugs are likely fouled due to the incomplete burn caused by a weak coil. Despite this, I'd highly suggest replacing with another Toyota coil because the aftermarket ones don't last very long and they typically do not come with a warranty.

Hope this helps!