Why not just replace the valve, a 1994 engine would need one by now...they don't last forever and the sensor that reads the valve position would be worn out. Easy enough to measure the resistance of the sensor with a DVOM if needed but I doubt you will find its any good, those diaphrams that actuate the valve are just a type of synthetic rubber and crack which causes all kinds of issues.
In my experience cleaning them is a waste of time, its almost never the valve itself...its either the sensor or the diaphram. Another option is the junkyard, you never know you could find a recently replaced one on another vehicle...any vehicle with that engine would be a candidate for a swap.
“She may not look like much, but she's got it where it counts, kid. I've made a lot of special modifications myself.”
— Han Solo