Yet another no starting renix.

A few weeks ago I thuroughly cleaned the throttle body and it ran like a champ, passed smog with colors and decided to get a dynomx still ran like a champ. So I then decided to make my own cone filter set up. She drove strong for a day but at the end of the day it wouldn't even turn over. Put my roomates battery in it and it sarted right up took the battery out and drove home. Soo the alternater must be good. Got it home same thing. Took my battery to get recharged and she started right up. Drove it to the pick and pull on sunrise and nooo start again. Replaced the sarter there and tryed someone elses battery and still no start. Tried arcing the starter soleniod next to the battery with a screwdriver. no go. I can still hear it clicking when I try to start so the solinoid should be fine. I don't have a voltometer yet so I havnt tried for any volt readings as of now. When i was getting pulled to safty my dash lights would go on and off when they felt like it, while battery cables were taut and secure. I also changed the fuel filter a couple weeks ago and fuel pump was replaced 3 years and 25,000 miles ago so fuel pressure should be fine. its an 87 4.0aw4np242
Any thoughts?

So when you put a different battery in it, or charge your battery after your xj sits for awhile it starts right up? Mine did that. It was the alternator. One of the diodes shorted out and it kept running the battery down