H90XMS LOO5V replaced heads, cap, rotor, plugs, wires, alternator, crank sensor, cam sensor, coil and igniter. no mil lamp codes. Can't access computer for data stream for lack of software. tier II (2005) spectrum. Experience has shown that delay timers don't usually help. Engine timing is correct as is firing order. Added grounds for electrical components including computer. Have two machines with this problem. Did cap test for GM 4.3, and cap is ok. Engine is too close to body of truck to pull and install plug wires one at a time while engine running. any ideas ? I can't be the only one with this problem. Thanks in advance