temp sensor resistance (for ecu)

Here's the story: My 87 is getting bad gas mileage and I have been trying to improve it (plugs, wires, O2 sensor, tested TPS sensor, fuel injector cleaner, clean throttle body, etc.). My temp always reads low so I replaced the thermostat with a 195* one from the dealer with no change. I thought that maybe I was not getting into the closed loop and therefore running rich so I was going to test and possibly replace the temp sensor. I poked around in my 87 factory electrical troubleshooting manual in preparation and it looks like the sensor for the gauge and the sensor for the ecu are different (the one for the gauge is on the back of the engine by the valve cover and the one for the ecu is on the driver's side of the engine, coming from the same harness as the O2 and knock sensors). If this is correct then what my gauge is reading has nothing to do with getting into the closed loop or not. I want to test the ecu temp sensor but I can only find resistance values for gauge temp sensor.
Does anyone know how I can test this sensor? Is it the same perhaps (I have not yet removed it)?
Better yet, does anyone know how to confirm whether or not I am getting in the "closed loop"?

The CTS is a larger plug than the sender and has qty=2 wires ...
... you'll see it on the driver's side of the block near the knock sensor (the knock sensor has the shielded harness and the goofy plug - the CTS is the other one with qty=2 wires coming right out of it) - you can measure the resistance across those qty=2 wires to test it -- remember that your head temp (indicated by the dash gauge) is not the same temp-value as seen in the rest of the block - like where the CTS is located.


Ordinarily, I'd say watch the ALFACALvalue on the ECU (tough to do without a DRB scanner!) to see if you're in open or closed loop - the Value should be something other than 128 -- not that you could tell...
... without the scanner - I watch the injector pulse width on a warmed and idling engine (I also hold the IAC open a bit to force the base idle to about 1200rpm to ensure that the O2 sensor won't cool off and drop out of Closed Loop) -- while watching the pulse width at a fixed RPM, add propane to the intake system (I use a t-fitting in the MAP line - a drop line into the TB's idle control port will do as well) to richen the mixture -- If you're in open loop the injector pulse width will NOT change - in Closed loop your injection width will vary with and without the propane enrichment-- TRY SEVERAL TIMES shutting the engine down after each test -- if you hit the full rich point the ECU will default itself to open loop and not reset until the next restart. (if you were watching the ECU's ALFACAL data the value would drop to "0" when you went full on rich - the snap back to 128 as a open loop fail-over!)


Resistance:
212*F = 185ohms
160*F = 450ohms
100*F = 1600ohms
70*F = 3400ohms
40*F = 7500ohms
20*F = 13500ohms
0*F = 25000ohms
-40*F = 100700ohms
-- pretty standard values for NTC thermistors (all of the thermistors on RenixII era XJs use these values)