Rough idle - 1996 Suburban

[raustin1448]

Hello,
My 1996 Vortech 350 Suburban is getting engine codes 300 and 1153. There is a rough idle at stoplights and above 2500 rpm it is smooth. New platinum plugs, wires, rotor, cap, and intake air sensor.

Any help would be appreciated!

[PACTKE]

chevy's dont like the platinum plugs , but that prob. isn't it. go ac delco... I've tried them all... most are coming with 100k iridium plugs($10 per) There is a site alldata that has a fee $ 24, that is real informative. your codes are o2 sensor(insufficient switching pre converter right bank) and engine misfire

[Fireplug]

Po300 missfire, 1153 injector number 3 problem
This engine does use platinum plugs.
Run some good injector cleaner in the fuel tank. You might have picked up some dirt chnage the fuel filter also. After a tank or 2 of gas with injector cleaner in it and you still have the problem you will need to check the enjector