I have a 1994 FJ80, I noticed that I was loosing water from my radiator and had my head gasket replaced. Seems to have fixed the water problem. However, Since I got my truck back if I try to drive the truck before it completely warms up and the idle kicks off it will not shift into overdrive. When the idle does kick off my check engine light comes on and then the truck will shift into overdrive. In addition after the truck warms up I noticed a very faint "tick" sound when I accelerate from a stop or going up a hill. I have had a mechanic look into this and they could not figure out the problem. They did inform me that it was was not a transmission problem. None of these problems existed before I had the head gasket replaced. Can you help!!!!