Won't Start

The truck has 135,000 miles on it, but has never given me any problem. Until now. I change the oil every 2,500 miles, keep the ignition system updated (plugs, distributor cap, rotor, etc.) But all of a sudden my truck won't start. The fuel pump kicks on when the key is turned on, I've cleaned those pesky battery terminals that later model Chevrolets have, and I've removed the spark plugs to test for fire and it seems to be firing alright. Before I saw it was firing, I had the ignition control module tested, and it was fine. I've double-checked the timing, and it hasn't jumped time. A buddy of mine had the bright idea to spray ether into the throttle while I cranked it. Still didn't start, so I know it can't be a fuel problem. Not only did it not start, it didn't even try to fire. If it's not a fuel problem, and the motor is cranking and the ignition is firing, I'm assuming it's something electronical somewhere that is over my old-school head. I plugged a diagnostic unit into the truck just to make sure, and it showed no codes; however I realize any codes would have been erased when I cleaned the battery terminals. Yet, I'm not sure it would have given a code anyways, as the check engine light never came on. My best assumption is that a sensor somewhere is not referencing and is telling the engine not to start, though it has all the necessary components to do so. I never ever take a vehicle to a "professional", as I won't let the truck defeat me! Besides, half or better of the "mechanics" out there are just guys like me intending to make some money off cheating people who have a bad $3.00 thermostat or so forth. Anyways away from that tangent. Is there someone who has a better understanding of the electrical system than I do who realizes what's wrong here? One more thing. The truck didn't start one day about a month ago. I came back about a week later and it started fine, over and over. Then about two days later I went back to start it, and it hasn't fired even a little. The first time I tried to crank it and it wouldn't start, it would putter a little bit every few seconds, which initiated our whole 'jumped time' theory, but now it does nothing and is in time. I don't if that information helps, but this whole situation has me bumfuzzled. I was told it could be the cam or crank or both position sensors, but I have no way of knowing for sure. I may replace those both ($100.00) and still have an engine that doesn't start. Thanks for reading this.
Cody

P.S. Temperature also has no effect on the engine starting, as this was another failed theory of mine. I tried to start it on a warm day, with a jumped battery. And nothing?