ECT Sensor: Front motor intake manifold coolant cross over.
Act Sensor: Don't know
PCV; Right hand motor valve cover.
VSS Sensor: 1999-2004 GT does not have one. It uses an OSS sensor instead. Located on the transmission tail shaft.
Thanks burns. You've been a big help. Hopefully you will help me get my stang running back to full potential. I think I had issues before hand that needed fix before I got it tuned. So hopefully after everything it will run better.