Well, your last post shows it pretty tore down, but I'll give you what I know anyway, since I happen to own a V6 truck and have done lots of troubleshooting myself.

Since you say that you have spark I'll assume that your ICM is fine, but you have to make double sure that your plug wires are in the correct order. Unlike almost every other engine (in my experience at least), the 6G72 cap has the rotor contacts in different locations than the wire terminals. If you look on the inside of the cap you'll notice that there are raised portions leading from the wire terminals to the rotor contacts. The cap should be wired 6-4-5-3-1-2, clockwise, starting from the terminal closest to the oil fill cap. Despite that, the firing order is actually 1-2-3-4-5-6 (as you probably know). When you put the distributor back in, the rotor should be pointing directly at the firewall at TDC #1.

If that isn't your issue (it was mine at one point, and the symptoms matched yours pretty well), you can eliminate the ECU as your problem by hooking up a noid light to an injector plug to make sure that they are in fact getting pulse. That's all I got. That bad fuel you found couldn't have been helping anything, and it never hurts to clean up an old motor. Hope you get it back on the road without much more trouble .