“Starving ISIS”
Not sure that makes sense.
Most of ISIS wells are in Iraq, and some in Syria.
I will guess that ISIS production costs are reasonably close to Saudi production costs, which are around $10 per barrel.
I read the production in that area is down to 20% of what it was before their presence. Wells are not magic machines. It does take some effort to maintain. At the same time, their sales appear to be at prices 25~50% of the market rate. Their buyers don't take the risk of dealing with them without their own benefit.
If the market prices fall, so are their prices as well, and to a far lower rate.