D-Jet brains sell on eBay occasionally for $25 or $20. They rarely go bad - so there is little demand for them You might just try picking one up from there to have as a spare.

Also - are you checking the seonsor readings at the sensor or at the big multiplug at the computer? Checking them there (consult a wiring diagram for the proper connection) checks the wiring as well at the same time.

As already mentioned take out those distributor contacts and give them a cleaning. You might also try cleaning the throttle switch - though that doesn't have anything to do with the injectors firing normally but it doest trigger extra injector firings as the throttle is squeezed open. I don't know if a problem there could interfere with the normal firings or not.