temp gauge erratic, runs rough

[Daddy]

I posted this prob. in the 24 valve forum a week ago and only got one response. I still havent resolved this. When I start the truck cold it is running very rough and when it this is happening the temp gauge is all over the place. It seems to go away completely when fully warmed up, and it doesnt do it every time. It will go a couple of days and work perfect and then act up again. The first thing I did was replace the coolant temp sensor, didnt help. Then it was suggested by a forum member to replace the wire connector to the sensor. My dealer couldnt even find the part # for the connector. The forum member got a part # for me and I ordered it but it wasnt right (they must have changed connectors, my truck is 99 I think his was a y2k). The check engine light comes on when its acting up but my 99 wont show the codes on the odometer. I also tried this, when it is running right and you unplug the sensor the gauge goes to 0. When its acting up and you unplug the sensor the gauge still swings all over the place. To eliminate a (short in the connector type) of problem that was suggested to me I even cut one of the wires while it was acting up and that didnt change any thing. Maybe I am going about troubleshooting this all wrong but I feel that I have eliminated the problem being the sensor or the connector. Does the signal go to the pcm or the ecm from the sensor? Could it be another sensor that would seem unrelated but be causing the trouble? Please help, its going to the dealer next week if I cant get it figured out.