Car shakes/rocks at complete stops and makes a little noise, also sound like it doesnt want to start sometimes

Hello, I have a Saturn aura xr 2007 3.6L, v6 and on Feb 28 2015 when headed to work 6am my car acted as it didn't want to start now I don't now if its because of the cold weather but it started it let it sit and run for 5-10 min and left. It drove fine no noises but only when I come to a complete stop is when it begun to rock/shake and make a little noise. Thinking it was from the cold I didn't worry but when I left work that even the temperature was warmer but it was doing the same thing as in the morning start and all so I decided to take it to a shop where they had run diagnostics they said I had several codes pending but the only one that wasn't was the camshaft timing and that all they said and did. And that all they said and did. Months before I went to a few places and they all said what they notice to be done is. Intake, crankshaft oil seal, cooling flush and camshaft position sensor so far I haven't been able to get any of that done also one place I trusted said to me there is no major leak and the sensor good just be bad but its not major to take care of at the moment. Now a little more history a few months before then I begun to put unleaded plus in my care rather then unleaded to save what is recommend is unleaded with a octane of 87 or higher I'm not sure what the octane has been those time when I put unleaded plus but as looking up things online there was a forum about "spark knock" I don't know too much about cars and what issues are greater then others so I have to trust that where I take my car they are knowledgeable and experienced. Help please thank you.