Question about 4.6 wiring...

There was a MAJOR change in the Mustang starting in 1999. I would be very concerned about mixing wiring harness accross this MY change.

You really need to pick up a Ford service CD off of ebay. The CD will have the wiring diagram for all cars in the model year. This will allow you to compare the differences.

Do you have an ODB2 scanner? If you had the ability to monitor operational data, this might tell you what sensor input is missing that is preventing proper operation. Without setting down and actually comparing the differences in the harness, I could begin to tell you if the t-bird harness can be adapted.

It would also be handy to know where the other parts of the puzzle came from. For example, what about body harness? Remember there are differences between the V6 and GT versions of Mustangs. You have the added complexivity of an additional make/model car.

Yes the pre-PI coil pack cars can be converted to COP. IMO, this is adding another layer to the problem. One that you do not need.

Good luck to you.

One quick question, why not put the 4.6 in a 99+ mustang, just out of curiosity. Some of the most talented mechanics run into problems w/the kind of swap you're doing!