No spark on three cylinders driver's side?

Yep, it sounds like the coil drivers inside the PCM have gone bad, can I ask if you had the PCM pre-programmed? If not, this will be the problem. The PCM must be programmed to the truck to work correctly, you can get a preprogrammed unit by searching Google or Ebay.

Here is how to replace the PCM correctly. Check out the images (below). Please let us know what happens. You may have a crankshaft sensor that is weak and produces an erratic signal to the PCM FYI.