This is what I recommended JJ! And still do! Different place different switch!
Greg

 

I have no direct knowledge on the subject.

The S57 diagrams show it as being normally closed.

One side of the fuel temp switch gets 5v from the TPS circuit. The other side of the switch goes to the Air Temp Sensor. So, when the fuel temp switch opens, the Air Temp Sensor doesn't get the 5v signal, rendering it inoperative....just as though it had been disconnected.

As I understand things this would richen the mixture.

Cheers
DD

 

If this is the case Doug; and the switch is open (ie in this case when the wires are NOT connected) this has the same effect as disconnecting the A/T sensor plug. And this does indeed richen the mixture. JJ said when he DISCONNECTED the two wires the idle improved (even if he thinks it still missed a bit underneath the improvement).
Therefore, JJ, the improvement occurred when you richened the mixture by disconnecting the two wires.
Therefore JJ, maybe your ECU is set a bit weak at idle?

 

That is possible. Or a leprechaun lives in the intake manifold and I get misses when he moves from kitchen to living room. Both equally likely from my testing.