Do all 1994 Ford Ranger 40 have an EGR Valve?

No, not all 1994 Ford Ranger 4.0L engines had an EGR valve. The presence of an EGR valve depended on the specific emissions standards the truck was built to meet. Some 1994 models built for California or other stricter emission states *would* have an EGR system, while others built for less stringent areas *might not*. You'd need to check the vehicle's emission sticker or consult a parts catalog with the vehicle's VIN to be certain.