98 K1500 missing

98 K1500 missing after replacing spark plugs. Ran smooth before. Have replaced plugs again, plug wires, cap and rotor, fuel filter, and cam position sensor (computer showed 30deg mismatch between cam and crank). Plugs and wires replaced twice with no change. Odd that a fuel injector would plug or quit while changing plugs, but can not think of another cause. I have verified a strong spark at all 8 plugs.

Looking for any suggestion before R&R of injector assembly...

Also, the engine turns over VERY slowly and is hard to start. Battery tests ok, cables new. No check engine light or new codes.

Double check the wires, it almost sounds like a few are in the wrong spot, the cylinder number is usually on the distributor cap. Did it turn over at normal speed before the plugs were changed as it does sound like a timing issue. 30 degree cam retard or camshaft offset, can you give any other recent maintenance that has been done, was it -30 degrees? It may indicate some serious distributor gear wear. Does your check engine light work, at 30 degrees off it should have set a P1345 code?

30 degree camshsft retard will give a engine miss.

Check cam shaft senser in dist and the plugin to it.
Is it pluged in?
Pin on sensor plug in sometimes get bent over when pluging in the wire.

Did you have it unpluged for any reason?

I have checked the wires and the firing order multiple times. All wires get full spark to each plug, I have replaced the cam position sensor and, yes, it is plugged in.

What kind of a miss? Constant or intermittent?

Did you use AC-Delco plugs and wires? Aftermarket caps and rotors can cause troubles also.

Timing on your vehicle can only be checked with a scan tool that can access "cam retard" or "cam offset". This is base timing and needs to be 0 +/- 2 degs. The VCM takes care of the timing after that is set.

Miss is constant.
Yes, AC Delco wires and Trittium plugs.
Timing within tolerance. No change made to timing since miss began. It ran normally, although had a power drop-off which is what caused me to replace the plugs in the first place.

It may be pluged in but is the pins bent over.
If it is reading 30 degrees camshaft retard the circuit/wiring is bad or sensor is bad or dist is way off.

What is the camshaft retard readings now?
Post back readings.

And see if there is much difference between the scanners rpm readings and the tach