Here's a coupon for that HF multimeter. Free with no purchase necessary.
As for speed/ref-sensors, TEST and DIAGNOSE
as bad BEFORE replacing. I've seen people replace speed/ref-sensors, spark-plugs, plug-wires, distributor/rotor, coil, injectors, fuel-pump, FPR, fuel-rail, DMEs & KLRs, DME relay, pretty much everything on the engine except for the engine itself. Only to find out at the very end it was the sensor-bracket that needed adjusting. You end up with a tonne of spares you won't need for decades by just swapping parts without testing & diagnosing.
This is the very 1st test that should be done. Hook up an oscilloscope to see the sensor signals. First, check for those signals at the sensor-plugs themselves in the engine-compartment. Then check those signals again at the DME-plug under the glove-box. This 2nd test will check the wiring-harness in between the sensors & DME. If the signals at the DME-plug doesn't match what you got at the sensor-plugs, then harness is bad. The 2nd test also verifies that you don't have the sensors swapped.
EVERYTHING starts with these signals. If they are not up to spec, nothing else will work. And most of the time, it's not even the sensors, it's just their height-adjustment above the flywheel that needs to be adjusted. Engine-vibrations can move the sensor-bracket over time.
Here's a
Speed/Ref sensor test & adjustment procedure at
Clark's garage
Here's some related threads:
Suspected bad DME
Home on a flatbed