I know this is a common problem since I've seen multiple 2nd gens do this, I searched, but came up empty handed.

This one baffles me because there's no real problem or harm being done.

When sitting at idle, the RPM's will drop and it will lope like it has a cam. It seriously sounds and acts like a big lift big duration cam, except with slightly higher RPM's. The truck will rock back and forth hard from the motor. There's no knock, sputter, stumble, etc.

What the hell is causing this? My only thought is that the computer's pulling timing out, a lot of timing, for some reason.

 

no engine light or code's??? you would think if it's running like that it would through a code of misfire??

 

Nothing. Like I said, I've seen multiple 2nd gens do this, none of which ever threw a code.

 

What was the out come on the 2nd gen trucks maybe start to look there? Try and unplug the battery maybe your computer is having a stroke, maybe needs to relearn.

 

do you have a programmer on it? my 4.7 does the same thing and it was from the hypertech. before programming it idled at 550 rpms. after programmed it idles at 500 rpms and it'll drop down to 350 then shoot up to 650 and so forth like its cammed.