My truck is a 1999 XLT 3.0, same as in the OP. Had the same problem but one of my lines became sheared at the connector to the plate. Because the part is no longer available except in salvage, my mechanic did the workaround. He closed up the holes, and rerouted the lines to the side. Have no idea how long it is going to hold. Just got the truck back today, got it on the expressway and had no problems. Hah, even the ABS lamp finally turned off.
Any ideas on how to clean up the mess is appreciated. Anyone who happens to have that intake manifold for sale from the same model, I would be interested in hearing from you, in case this mod doesn't hold.
Cheers.