Power issue when I turn the key to start

Does anyone know what my issue could be i have a 98 silverado with a 4.3 vortec my converter was pluged badly i had it cut out new exhaust put on with no converter put new plugs cap and rotor still runs rough and no power taking off sputters really bad i have too give it gas too keep up too speed on the road im confued help

Have you tried checking the coil out ? its likely the coil has gone bad in the car which would cause no starting either that or the battery is toast.

Thanks. I'll try that