So i have a 04 5.4 3v with 54000 on the clock. At idle in gear or in park i feel a little shake....ie not running smooth. I have no other issues. I have a warranty on the vehicle from a reputable chevy dealer so i brought it to them today. They say nothing is wrong but to me it doesnt feel right. anyone have the same problem or advice?

 

Put 91/93 in it, change the fuel filter, plugs, COPs, any fuel/ignition related things. I'd bet it goes away with a higher octane fuel or a filter change.

 

I have the same problem, mine has the shakes at idle and in gear with brake on, once an a while it will go away, I have been figuring it is the plugs, I have 110000Km on it, not sure if the plugs were changed before me, I am waiting for a long weekend when I don't need to go any were, it is my only source of transportation. And I gotta tell ya I am a little scared to take them out after reading about it on here....

 

Change the fuel filter and clean the MAF.