Warning, I am getting on my soapbox 
For years we’ve been back and forth on this forum about the CPS and speed sensors on Marelli cars. Resistance, temperature, wiggle the leads, how to test, etc, etc.
My .02: If you are going to drive a Marelli car (I do) then you need an oscilloscope. There are several sub-$100 handhelds on Amazon that will do the trick. The ROM is very clear on how to test using a scope.
If you really want to make you life easy, crack open the passenger side foot well and carefully tap into the Marelli injection computer harness. I wired in a simple harness that allow me to see the 3? wave forms that are expected here. (I think it’s CPS, engine speed and a pulse to? the ECU in the trunk…) The ROM is clear on this as well, I am going from memory at the moment. The end of my harness is up under the glove box. I keep the scope in the boot. I can do an initial sensor troubleshoot in about 1 minute. This allows me to confirm the sensor function and wiring all the way to the Marelli computer. If one is bad, I can start working backwards towards the sensor, checking things like the goofy white wire on the left side of the fuel rail, sensor plugs, etc. It also tells me that the Marelli computer is outputting the pulse that it is supposed to the ECU.
For about $100 and a couple of hours of careful interior panel disassembly and soldering, my sensor worries are now minimal.
Off soapbox!
Bob
