Outer Limits 4x4 Board

G'day, I replaced the engine in the 88 NF about 8 weeks ago. All good for a while until recently the idle speed has been climbing, won't idle at less than 1500 - 1800 RPM. I have readjusted the timing to spec. and this has lowered the idle a little to around 1000-1100rpm. No air con on in neutral. auto trans. 3.0 v6 came from 1992 NH?

Is it like that all the time or just when you start it up?

My 91 NH tends to idle at 1500rpm for a fair while until it's at operating temp then it varies between 750 and 1000rpm.

Idle stays high well after full temp has been reached. In some cases does not come down at all. Idle speed is set by coolant temp going into solenoid correct? Any way to check proper operation of solenoid?

There is an idle bypass srew at the back of the throttle body, leaning towards the firewall. Turn it in to lower the idle. If it still idles high then you may have a crook idle solenoid or cold start solenoid.(the thing with water hoses going into it)

Thanks. I'll give that a go. I appreciate the your responses.