[Canucklehead]

Was your last "upgrade" the alternaor?

I just read your chrome alternator post, are you sure the belt isn't slipping? This would kind of explain your battery not charging. Although I'm not familiar with 4 cyl. Amigos, I assume it has a voltmeter on the instrument cluster. If/when you can get the engine started what voltage does it read? It should read around 14V normally. If it is reading low your alternator either isn't spinning fast enough for the voltage reg to maintain voltage, or the voltage reg is bad.

 

[Canucklehead]

If you have a voltmeter you can check the voltage at the battery while the truck is running. As I said before it should be ~14V when running and ~12V when the engine isn't running. Also, you should be able to take the alternator into an Autozone or PepBoys and have them test it for you.