I have a 1997 Galant with a Dohc 4g63 swap (from a 2006 outlander) The engine works great, but the idle is kinda "wonky". It runs normaly, too low or too high no matter the temperature of the engine . I have replaced the IAC sensor and MAF sensor, but nothing helped. There is a new coned filter on the engine, so it gets fresh clean air. I have cleaned the throttlebody and cleaned and checked the EGR valve for wear and tear.

The car had the same problem with the old sohc engine (which blew up at 219.000km). New engine has run 37.000km as the car is now.
Sometimes when the car idles too high at 2500rpm, i can boop the throttle and it starts jumping between 1200rpm and 1800rpm. When the idle is low it runs around 100-200rpm.
When the idle is "normal" it stays calmly around 900-1200rpm.

Any help would be apreciated. ​​​​​​​