I have the 1jzgte and have had idle troubl when engie hasn't warmed up all the way. Have had a look on the net. aparrently someone has fixed the same problem by "take out and clean your ISCV" What is an ISCV and where is it.

i wish it was that easy lol

but hey... try it... who knows it might be your problem

isc is the idle control valve, on the 1jz i believe it is at the back of the intake manifold closest to the firewall... has quite a large round unit bolted on by two bolts, inside that is the little disc which is a filter and black rubber o seal

pull em out, clean up the filter or see if you can possibly get a new one and just clean out where the filter sits

lmk if this does fix ur idle problem :)