sounds more like a bad wire problem to me, you could do what is known as a shake test start the engine, let it idle then start grabbing wiring harnesses, and shake them vigourisly (spl?) if it stumbles then your problem is in that harness. If that doesn't find anything next check ALL of your grounds a corroded ground will act like that sometimes. Another test you could try is known as a tap test (operative word TAP not bang on it with a hammer test) with the engine running tap on the sensors, and the ecm if it stumbles you found you bad component. I worked for GM, and in the early 90s they had a problem with the MAF sensor on certian cars it would idle fine, and usually ran ok but it would just die going down the road with no codes or warning, and you could run the tester on them till pigs fly, and never find it but if you tappped the sensor the car would die. and they also found that ecms have a problem with the soldering (any manufactorer has this problem not just GM) and TAPPING it will cause it to stumble, thus leading to the replacing of said component.
YOu might also try posting this in the other forums for the proper engine, or maybe for your truck