Having problems with your 1993 GMC Sierra K1500 ?
Truck jerks at 60 mph - 1993 GMC Sierra K1500
I agree with Jerry Ross, at the same time you could have one weak wire or a bad cap. Once you take off the motor is no longer under a load so any intermittent misfire will come out of nowhere. Cap, plugs wires. Or a bad engine ground, I would start at the cap and clean it or replace it if it is badly burned. Wires ground them out one at a time if you have a bad the spark will ground out.
Sounds as if you need to be sure plugs are not fowling out and be sure fire from dist and coil is ok.
Repair Help & Product Troubleshooting for 1993 GMC Sierra K1500
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