Ran into an issue with mine when someone overfilled it with oil. I drained 7 qts out, refilled it with 4.5 qts new, back to normal idle and I do my own oil changes now.

 

Kc2k what year and model u have?

 

Mine is an '03 SS with a L67 out of an '04 SS. Symptoms sound SO similar. Runs fine at rpm, but vibration at idle that looked like a loose motor mount or something. Couldn't believe it was the extra oil doing that, but it sure was.

 

Here's my two cents worth. My 2001 SS with the 3.8 idles rough and runs rough when driving 20mph through town. I traced mine down to the throttle position sensor. Since the sweep inside the sensor passes through the minimum position the most, you get the most wear on that resistive part of the sensor. I checked mine with an ohm meter by measuring the resistance at the prongs that the plug fits onto. Hook your meter up here and slowly rotate the sensor. If the sensor is good, then the meter reading should be smooth and proportional. If it is bad, the needle should jump around at the point the sensor is bad. This jumping around is where your rough idle comes from. The computer is compensating for the readings it is getting. I'll bet that when you take off in the car the motor runs just fine when you have to push the pedal down just enough to get past that bad place in your sensor. Mine does. I hope this helps. It may not be your problem but it is something you can check. The last time I checked the sensors were about $75.

 

Hey guys thanks for your replys..........when i start to drive the car is totally fine its when the car is still that it runs rough alittle though...........and i just had the oil changed it took 4 1/2 quarts

 

Well I know I need my tranny serviced (33059 miles) I also need throttle body cleaned????? Idk what that is.....and fuel injector serviced also so idk if it could be those things

 

GM recommends the throttle body and fuel injector cleaning at around 25k miles. It's not a bad idea, but probably not REALLY necessary for most cars. It's one of those thinks you could hold off on if you wanted to, but since you are having an idling issue already, why not get it done and rule it out? I'd go for it. By the way, throttle body cleaning is something the DIY'er could tackle. FI cleaning - not so much as it requires some special equipment to do right.

 

Could those issues needing to be done causeing the rough idle????? I just want it to be good!