Hello folks, new here to the site. Just bought a used 2000 Malibu with 137k with a V6. Car runs good on the highway but on a red light it has a rough idle almost wants to turn off. I just replaced the oil and filter and did a raditor flush and fill. Order AC Delco fuel filter, PCV valve, Air Filter. What else should i be checking, there is no check engine light on and the engine looks good overall. Thank you in advance for your help.

 

Check the plugs, and while you're at it dump a can of BG 44K in the gas tank.

 

also check the fuel regulator could be its cloaging up and going to fail soon i had the same probrom changed the filter and it worked for a bit then it will turn off when i stop on a red light checked the fuel regulator and there was no fuel flowing though it should have a little fuel coming in there so i changed it and it worked. just check maybe its the same thing