Your Ford Ranger's EGR valve makes it possible for your vehicle to effectively recycle spent exhaust gasses back into the combustion chamber for a more complete burning. This helps reduce NOX, or nitrogen oxide emissions from escaping into the atmosphere. Over time, your Ranger's EGR valve will become clogged with carbon. This is considered normal wear, but will cause the valve to stick and when that happens, your Ranger will perform poorly at idle and will hesitate on acceleration.
Turn the valve on its side and use the pick tool to dislodge any loose carbon deposits from both valve openings. Be careful on the bottom valve opening that you do not damage the threads.
Spray the valve openings on the Ranger with carburettor cleaner.
Scrub the valve openings with a pipe cleaning tool. If you are having trouble removing the carbon, you may need to put some carburettor cleaner into a small catch pan and allow the valves to soak in it overnight. Only soak the valve openings. Do not submerge the entire unit.
Wipe down the EGR valve assembly and make sure that you've removed most or all of the carbon build up before reinstalling the valve.