S14s have milder cams than the S13s due to deletion of the butterflies in the intake manifold. Timing light is only going to be able to verify ignition timing. If you had the timing set apart you'd have to pull the timing cover off and verify timing marks on the cam gears/crank/idler to verify valve timing.
There are a lot of things to look at but the sputtering may be a fuel issue as well. Do you have a wideband or any way to check if it's running lean/rich?
As far as setting ignition timing, this is still the best resource I know of, to date.
https://www.nicoclub.com/archives/240sx ... iming.html
I use a paint marker on the OEM crank pulley to make it easier to read. that IS your timing. If you have poor throttle response at that point it's either a fueling or an air issue most likely (assuming you haven't had the motor apart) but, again, this won't rule out a valve timing issue.
What does your engine idle at, as far as RPM? Have you done a vacuum leak test? What's the back story on the engine, did you just buy a used one and swap it in or...? What are the unknown variables here basically.