rough exceleration,not smooth

1994 blazer 4.3 vortec 121,600K miles ,idles great,after it warms up , runs out ,at highway speeds really nice, but on normal exceleration it seems abit rough ( not smooth ) ,no misfires. i've installed new rotor cap,rotor buttom ,plugs and wires, pcv valve. any suggestions wound be greatly appreciated. haven't replaced the fuel filter yet , i can't get the old one off. i guess i'll have to get new hard lines.

Did you replace the fuel filter?