What Is This Part, Should It Be Like This?

[nickhill]

I have a 2.3 auto 1997 Galaxy.

 

Following an issue with an overheating engine (caused by a friend driving it around without a fan) it has developed an irratic tick over, it gets far worse when the engine is hot.

 

I have replaced the engine temperature sender but it has not made a significant difference.

 

Whilts replacing the sensor I notice the part in the attached picture which is attached to the right hand side of the engine. It seemed rather odd to me that it only has 1 electrical wire coming out of it but it has a plug that appears to accomodate 2 wires. I cannot find any loose wiring in the engine bay.

 

Does anyone know what this part is and if it is supposed to have 2 wires coming out of it and if so, where the second wire might emerge from?

 

Anybody got any suggestions as to what could be causing the irratic tick over?