1991 Jeep Laredo

I recently took this truck all the way from CA to NJ with no problems. Just the other day, I was driving down a pedestrian street and it started to coast to a stop without any warning. I knew that I was dealing with a possible fuel system problem and thought nothing of it. I started by checking the fuel pressure at the test port and noticed that it was low. I worked my way back to realize that the fuel filter was probably the original that came with the truck. I changed it and checked the fuel pump, fuel pump relay, etc and have restored fuel pressure to the fuel line. I then tried to start it up again and it wants to turn over, but now I can't get it to start. I thought I needed to charge the battery, but when I went to the parts store they said it was fine. I am now in the process of ripping the alternator out. I fear it may be the Powertrain Control Module/Electronic Control Unit? I say this because my truck was having a hard time uphillls (could also be the clogged fuel filter), and a lot of the gages in the car were going a bit cooky a few days back. The battery says it has little voltage etc. Not to mention (if I have correctly identified it on my truck) it has a bit of corrosion on it from the battery. I think it is located in front of the relay box, bolted to the relay box. It is black and about 1 1/2" wide and 2" long. How do you check one of those units? Please help. Thanks.