my temp guage goes on and off like the wire from the sender is off which it has good connection new sender the one on passerger side. I changed it twice because I thought I got a bad sender. They connector seems to have a good connection

 

try watching the gauge and have someone wiggle the wire, its possible the end is good but the wire attaching to the end is barely connected

 

doesn't seem to change wiggling, when I let it get up to temp idling when I give it gas and them let off it the gauge will move up then down again I think it might be corrostion inside the connector