If you bought any opti other than GM, Delco, or Delphi, your problem is probably a defective opti. Of course doing a engine swap to your chevy truck, you could have got some wiring messed up.
So to 100 check your optical section of opti, you need an oscilloscope to check low & high resolution pulses sent from opti to pcm.
Lucky for you, a PC based scope can be bought on Ebay, Amazon, etc, for around $70. Use the scope to see if the low & high res square waves are being sent to pcm.
You can also download the 96 service manual at the following link. It will have wiring diagrams, and tests for ignition problems.
www.mediafire.com/?40mfgeoe4ctti
If your chevy has an ALDL installed, you can read the codes, if present. There are several codes that don't light the service engine light. These codes include low & high res pulse missing. And 2 ICM related codes. All these codes, except high res pulse missing, will prevent spark and fuel injector opening.
