My 2000 K2500 7.4 chevy has a miss at idle but it goes away at higher rpm's it has been doing it since 100000 miles and now has 170000 and has never gotten worse sparkplugs, wires, cap, rotor, fuel pressure reg are all new and nothing has seems to fix it i had a scanner on it and it said the #2 cylinder is the one missing. I could use some helpful ideas. I think that it could be an injector but I dont want to replace them if it could be something else.

SOURCE: I have 250000 miles on

If you have replaced the timing chain please disregard my answer, I'm risking my rating because I want to help you for free.
If the timing chain has not been changed that the problem might be an overstretched timing chain.

As timing chain accumulate mileage, chain stretch, sprockets wear out, and set the valves off timing. Most chains go up to 100000 miles or more, but not always. As a rule when there is more than about half inch of play between the gears on a V6 or V8, it is the time for a new timing chain and sprockets.
It is not unusual for a timing chain to accumulate 200000miles, but I remember a car, with broken timing chain, with only 160000miles on it, the valves were bent and a hole was put on the piston.

Signs of worn out timing chains are:
Rough idle.
Sluggish performance and poor economy.
Sudden engine performance change including the inability to start the engine.
Intermittent backfire through the intake manifold.
Inconsistent ignition timing or a clattering noise coming from the front of the engine.
It is a good idea to replace the water pump (coolant pump), and the thermostat while replacing the timing chain.
The cost of the replace of timing chain is at least +$1300, but if is to bad, we pull out engine and replace both guides. In this case might cost more.
Please do not be mad with me. I'm a certified dealer, and I'm trying to give you the necessary information to help you to deal with the problem.