The trans issue sounds like smoked 3-4 clutches. Might have a trans guy look at it.

03-04 are notorious for speedo problems but usually it's just inoperable or sticking, not jumping. Wiring issues at the VSS connector are common. Check both the green and the purple wires for stands broken inside the insulation. Also, if it's 4WD there is another connector just a foot or so from where it plugs into the VSS...it's a jumper to accommodate the 4WD wiring harness. Check for damage there as well.

Did you pull test all the wires individually at the throttle body as suggested my Madd Maxx and I? Did you check the black and white ground for PCM?