How do I find out why my car is misfiring? on 1993 Acura Vigor

car is misfiring at 3000 rpms & it wont shift unless gas is released & the engine knocks when is idling.
I already changed plugs & cables.

Asked by for the 1993 Acura Vigor
Any check engine light? Is it setting misfire code? Low/old oil? V-TEC system problem.