Erattic Shifting:(

[trackspeeder]

So after asking a few more questions, someone told me the speedo sensor has to be VIN matched. Could this possibly be my problem since I trusted the "experts" at good 'ol Autozone when they looked it up by year and motor?

Ford used two flavors of VSS. The first 89-91 Is tranny mounted (T case for 4X4). The second is mounted on the diff housing. No vin matching is required.

Check the FIPL voltage.