my 4.7 2004 has been idling at about 500-600 when im stopped or in park, It has not died on me yet. it also shakes. it has 60k miles on it right now, and i haven't changed the plugs. i don't know much of what the previous owner did to the truck, so i am not sure if he swapped in another cam or tuned it or ever replaced the plugs, i have been pretty **** about having the fluids changed with royal purple.

thanks in advance.

 

Start with replacing the plugs. Use the recommended plug in your owners manual. It's cheap insurance and then you will know they are fresh. 500rpm is fairly normal for a hot idle.

 

plugs, clean the back side of the throttle body, replace front O2s

thats where i would start