If you have an 89 GMC and it started missing very slugish on take off and almost stalling frequently when your driving what do you need to do?

clean/replace distributor cap clean/replace spark plugs replace spark plug wires fuel injector cleaner may help, if equiped with a TBI or injection carburetor cleaner for carbs. check timing change fuel filter. replace catalaytic converter. does it smoke. if so what color? (blue, burning oil, black flooding,etc) does exaust smell like fuel (first5),rotting eggs(cat.conv.). does it backfire or diesel ( timing,incomplete burning).