My Speedometer works intermittently, whens it stops working check engine light comes on. What do l need to replace?

most are Electric now days so it would be speed sensor

Make shop visit, let shop diagnose, let shop repair.

Their is a turbine shaft sensor in the trans and a VSS in the rear axle.

Why guess wrong on this?

If the ABS light is on also, change the rear speed sensor on the back-end housing in the middle

my guess is the VSS.

but a ford scanner will pinpoint the parts that you need to replace,but again this depend how good the tech on translating the code that they get

does the abs light come on or stay on also?

Usually as many have said has been the rear speed sensor on these years (the vehicle uses the rear speed sensor as well as the output shaft speed senor on the transmission which should cause a flashing overdrive light ) but would need to be scanned for the concern as it may be coincidence or other issues