Hello Everyone. I am LONG overdue JOINING the forum but always check it out as a guest. Thank you for taking the time to look at this post. I drive a 2007 Chevy Suburban LT3 with the 5.3 vortec. I bought it with 8 miles (new) and it now has 65,600 miles. I have never had such a close attachment to a material object like I have had with this car. I get EVERYTHING serviced at the dealer (oil tires etc) I even had the crazy idea of buying a carwash package card which afforded me the opportunity of washing it numerous times a week. I want to share that with you BECAUSE I want you all to know this car is babied! I moved from Maine to MN and put from July of 2009 to Feb. 2010 20,000 miles on it. Just recently after letting it sit for a month it is acting weird. It starts up fine and has all the power and sound it always has BUT EX: sitting at a stoplight it has an engine shake. The RPM needle shakes slightly, you can feel it in your feet on the floor. WHAT IS THE DEAL????? I don't believe its misfiring but it runs poor at idol. Any advice? Has someone experienced this with there Sub. OR 5.3? Thanks for your advice and time!!!! I will always offer advice to all of your posts if I can help! Take care.

 

Welcome to the forum..
is it possible you got a bad tank of gas?
Have you tried a fuel additive (I'd suggest a couple of bottles of Techron) to see if it clears it up..
check the coil packs for any damaged spark plug wire i.e. rub through or arcing
pull the plugs and inspect for gap...

 

When you let it sit for a month did you leave the gas tank full and/or put some fuel stablizer in it?

Also did you complete the 50k service yet?

 

My 07 did that and was embarrassed to have the dealer show me that #4 plug wire was disconnected. Don't know how as I had never touched them so guess factory didn't get it fully on. Easy check to make.

Oh and welcome to the forum.

 

You may also want to have your dealership take a look at what may be the issue. You should still have the 5 year 100,000 mile power train warranty which sounds like it should cover you for this fix, under normal circumstances. If you run into any problems or other issues feel free to contact me.

Jeff Morris, Chevrolet Customer Service