I'm no expert on cossie management but I imagine you would do the same as fitting an FRST EFi loom to an ERST loom. That is take the engine loom from a cossie and the full loom from an escort, strip the escort loom of all engine wires, then plug the two together in the middle for power etc. What loom do you think you've got and what engine are you plugging it up to?

Sounds like you have a stripped out escort loom if there are hardly any engine plugs.

Lee