MISFIRE advice, need expert and experience!

[kcobra]

Hey guys, I'm having big issues. 96 yukon with 5.7 vortec R-code. Has misfires from 1800-2500 rpm and then it goes away. Wot it runs fine. Cylinders 3,6,5 misfire. At about 2000 they stop firing completely sometimes. Here is what I have changed during trouble shooting and what I've checked so far. Plugs, wires, cap and rotor..still there...fuel filter..still there, pump and pressure are good, changed the complete fuel injector assembly as per recall that I found out a year to late! Problem is still there, module, still there, tried a different computer, still there. I'm at a loss of words. I don't know what else to change. Everything is new and the problem is still there. Oh yeah, new cam and crank sensors also. I just don't know anymore. The truck does have a car starter and I wonder if this could have messed up some wiring when the installed. Any help would be appreciated. Thanks.

[2000CAYukon]

Have you checked the dist drive gear for wear?

Does fuel pressure hold after ignition is turned off?

//2000CAYukon

[kcobra]

The fuel pressure is all good. The problem is spark, not fuel. Cylinder 3,6 and 5. As far as the distributor gear, I thought of it but haven't checked it yet because it doesn't make any sense. If it would be stripped or slipping it wouldn't stop only 3 cylinders from firing, the others would stop also. Like I said, between 1800-2500 there is no more spark on 3 cylinders, after those rpms and before the spark is there. It is very strange.