Hello, We have a E350 with the 5.4l engine that we use to haul kids for bible studies and we have blown the spark plug out of the head. I did install a helicoil kit but to me it was like tapping butter. Well it also blew out of the head. If this was not under such heavy loads all the time and such a large van I may just put a new head on it, but after all the research I have done, it looks like there is also rod, piston, and many other problems with this engine. I would hate to put money into this head and have lots of other problems down the road. I am thinking of putting a 6.2l in it but not sure if it is a direct fit. If anyone has a good economical idea on what we should do I would greatly appreciate it and I am sure the Lord will bless you.