Chevy s10 1999

Two things come to mind. First, given the age of the vehicle, if you have high mileage the timing chain could be worn which is why you saw the incorrect timing setting making you think it's not timed correctly. When the timing chain is worn both the ignition and valve timing will become retarded (late). Second, you must set the base ignition timing with the automatic transmission in drive, parking brake set, and the electronic timing advance unplugged. This will trigger the check engine light or service engine soon light but you can ignore it . If you have a manual transmission it should be in neutral, everything else is the same. Hope that helps!