do a compression check. if it is bad then have the dealership check it out. could be #6cyl...I have a 2013 silverado 5.3 Lc9 that shakes my seat at idle. The dealer said it's normal and started another truck on the show room floor which done the same thing. I have worked on chevy trucks since age 10 and had all chevy vehicals, but never had a erritating shake like this before. The dealer said put some miles on it then see. After 18000 miles I still have this vibration. What can i do?
my 2000 5.3L still idles very smooth ..155K miles.