2003 Mitsubishi Diamante Rough Idle

Hi everyone,

I have a 2003 Mitsubishi Diamante with a poor idle.
It is non-rythmic and at times idles smooth, at times really bad and most of the time just bad.

I have checked all the sensors, compression test, injectors replaced, idle RPM is steady, vacuum test, air leak test done etc

Took it to 2 mechanics who cannot diagnose it.

Changed plugs, leads, distributor, distributor cap, rotor, all filters etc.

PVC system is OK.

O2 sensor will be replaced soon but just hoping someone can suggest something?

It seems to be a common issue with these cars not idling well but no one knows the answer

sticking open egr valve?

I put a blanking plate on the EGR port and it made no difference.

Also when the hose is pulled off of the EGR solenoid and a vacuum pump the idle gets much worse so the valve seems operational

I just done diagnosing a 03 Mit Lancer with randon rough idle. In my case it was a faulty MAF that’ll drop out its signal intermittently. So check the MAF and Iac too. Hope this helps