I agree with the diesel first. We use the Baker product DFO8340. We have tried all of their products and that was the only one that worked. Bad thing is it is $52 per gallon. There may be some completion fluid still down the hole. If that is the case the foam problem should clear up after it is removed. If it is the completion fluid causing the problem then if the diesel works I would stay with it until the completion fluid is gone and your problem should be solved. What is the API? Is there any H2S present?