I was in the same boat. When cold it was hard to start like you mention and ran bad for a minute, as soon as the motor warmed up all was well.


I cleaned up the connection at the water thermo sensor and the cold idle smoothed out instantly.
My guess is I had too much resistance at the connector. sensor tested good...

1991 FJ 80 Land Cruiser for fun.
1998 GS300 for the wife
1998 GS400 for me
1991 Supra SOLD
1986 4Runner 335k miles-22re EB inside.SOLD