I have an 02 Ranger that pings really bad. I tried to get some new EGR parts from Autozone and the computers show that there is no EGR valve. What part of the system could be causing the problem?
Your cylinders are getting too hot. That can happen from too lean a mix (more air in the mix has the same effect as blowing on a flame with a bellows), carbon in the cylinders retaining heat, too hot a sparkplug, too low an octane gas, and…in many modern vehicles, don’t know about yours…a madfunctioning knock sensor system.
In an '02, carbon buildup is unlikely. I’d go with too lean a mix, probably caused by a malfunctioning sensor such as the oxygen sensor, or perhaps the computer has stored some codes that would give you some hints. Any Autozone will download it for free.
Another possible source of hints is the condition of the sparkplugs. The Champion sparkplug website used to have/has some good photos to compare them with and good explanations of what the conditions mean.
Check for a bulletin on pre-ignition on your truck. For several years your problem was common and a re-programming of the ECU quickly set things right.