I have heard the 3.9 dizzy would grenade... Well mine did in the '95 van at 100K Wednesday morning. A bunch of folks have said these 3.9s before 1999 could do that. The rotor shaft and all separated. If you can, check if you are running any magnum motor swap. I got lucky and just needed a new Distributor. A few can jam up things under the manifold. The tattletale is the sounds of clicking or rocks in the box noises.