We have a 2000 RV with a Ford V10 engine. we have had all of the spark plugs and coils replaced due to blown spark plug problems with this engine. Now it seems we are having the same problem again and the #5 plug cannot be removed. We are being told by the Ford dealer that it may break if they remove it and we would have to replace the engine. So, they say we should replace the engine now. How can this engine be fixed permanently? It is a serious problem Ford has caused between 1996 and 2002 V10 engines.