A common problem with your truck is that the water pump will leak. It is possible that there may be another reason your truck is leaking. I would ask for help from one of the mechanics at YourMechanic to come...
The PCM power diode is put into the fuel pump and PCM relay power circuit to prevent power surge feedback into the circuit called flyback voltage then can be higher than normal operating voltage. The computer may get flyback voltage...
The key and transponder that you are referring to are routinely vended by Automotive locksmiths, as well as on Ebay, Amazon, and so forth. All of these units require programming but that can be performed by local, albeit specialized, locksmiths...