Hi friends. Actually i have 2 problem which is on of them is same. By the way i have pajero 3.5 v6 24valve 6g74.
1- i have engine vibration on the idle. I checkd the engine mounts . Timing belt and also timing. Spark plug and wires changed . Oil changed . Vacuum leakage checked by splashing water around the manifold. Fuel pump checked and also the injection parts got clean. But still i have engine vibration at 700-850
2- after one hours driving engine start to lose the rpm to 550 eve
I lived on that adjustment for over a month too and felt exactly same as you explained. I also felt that Engine or ECU has some issue. In my case it was even more weird that once I start in morning RPM used to be dead low like 500, so bump up to 900 with screw and after 15 mins when car is warm it reaches to 1400. This exact is the job of Idle control Valve to keep maintaining ideal RPM in cold or warm engine in idling. I found that setting of 1200 when warm was perfect as when cold it drop to 6