At some point in the 90's the G & EPA added methanol(?) or some alky to gas to replace some other additive that was real bad for pollution. The early multitec injectors, 91 & back, were not designed with the alky in mind. The later ones, 92 & up I think, were redone to resist the alky.
In theory the multitec design lends it self to be a self cleaning injector. The alky with the early injectors does in the epoxy on the coil windings & the seals that are suppossed to keep it out....hence the coil shorting issues causing r&r of the older multitecs. That's the way I understand the situation.
Tom