Crankshaft Position Sensor; Learning Procedure?

Well, I have a 2000 Silverado with the 5.3L engine, and about 112,000 miles. I have a problem which no one has yet been able to diagnose (myself or dealers or private mechanics). The symptoms are lask of power in 1300-2000 RPM range. Initially, this would only happen occasionally, and initially it would also have no power when you tried to take off from a stop. Now it is primarily in gears 2-4. We think the problem must be a sensor somewhere that is giving bad info, but not bad enough for the computer to know it. Occasionally, the truck will wake up and run fine, but these days are getting fewer and farther between. Until this week, it had never thrown a code. This week, if I let it idle a while, it will throw either P0300 - Multiple Random Cylinder Misfire, or P-0303 - Cylinder 3 Misfire.

So, in reading about the sensors in my junky old haynes manual, I found that the crankshaft position sensor can throw these codes, particulary if they are replaced or "disturbed," and that it needs to have a "Variance Learning Procedure" performed by a dealer. I find it hard to believe that it would actually throw a false code, in that if it throws this code, the computer tries to compensate, giving you an actual problem.

I believe that my truck does misfire; I can remove any one plug wire, and then start the truck, and it appears to run no worse than before.

Now on to what has already been replaced in this process...
Air Filter
Fuel Filter
Fuel Pump (likely unrelated, but failing)
Spark Plugs
Plug Wires
Coil Packs (all 8; they were arcing faintly between the coil and the iron, and the new ones do to...)
MAF Sensor

CATs and exhaust system have been tested
TPS and MAP sensors have been backprobe tested
Fuel Pressure has been tested at Key on, Engine off, running , driving, and sitting for leakdown.
Fuel Injectors were tested.

I am sure I am leaving some things out here; any ideas or insight would be GREATLY appreciated.

Do you have a fuel pressure reading when the problem happens? If so, what was it?

//2000CAYukon

Fuel Pressures were:
56-60 idling, and 48-55 while driving, whether the truck was running well or not.

Not to sound sarcastic but sounds like you need to find a dealer with better mechanics. Driveability problems are not a mystery to someone who knows whats going on.