It is refreshing to see an articulate post. So many I receive are very difficult to read.
From 87 up to 94 there have been issues with the coolant temperature sensor. I have replaced many and I did learn to use a Toyota part.
I have also seen a lazy O2 sensor cause a cold issue but I am sure it has been replaced.
Was the knock sensor replaced when the head gaskets were replaced? It is under the intake. If it fails in at a set position it will retard the timing 4 degrees.
If you aren't belching black smoke in the morning most all cold issues are caused by a lean condition.
Let me know
Wednesday, May 31st, 2006 AT 7:39 AM