I just bought a 93 Ranger XLT with the 2.3L. So far I've replaced the plugs & wires, cleaned IAS & MAS, changed the oil & filter. The truck doesn't idle well & it's not constant. Sometimes it idles fine for a few minutes but then back to the rough idle. The idle thing is driving me nuts, any ideas? Thanks.

 

Spray some brake clean on the o2 sensors. Or replace them.

See if that helps.

 

First make absolutely certain that all vacuum lines, connections and manifold points have no leaks.

Remove the vacuum line from the EGR plugging it with something suitable. Does this make a difference? If yes, then get a hand vacuum pump/guage attaching it to the EGR to draw a vacuum on the EGR which if it is good the vacuum will not change or drop. The engine will stumble or die. It is now time to suspect your EGR solenoid which switches vacuum to the EGR depending on the RPM and rate of change of engine speed and load. If it is faulty you might be able to detect vacuum on the vacuum line to the EGR at idle by attaching a sensitive engine vacuum guage to the vacuum line seeing the guage needle bouncing slightly. If so then replace your EGR solenoid.

This is exactly the condition that I have determined was causing my engine to run rough at idle. As well it failed an E test running rich probably because the air fuel mix is diluted with oxygen poor exhaust gases.