Hey guys and gals,

I recently purchased a 2008 Silverado LT 5.3L V8 with 52,000km. After getting comfortable with the ride, I noticed a rough idle, in gear, while stopped. The rpms fluctuate between 400 and 750, it never stalls but I get a bogged out feel. During the fluctuation, the oil pressure drops slightly, lights dim/flicker, and, annoying vibration.

Plugs are original, runs in 87 octane.

Could anybody lead me in a certain direction as to what could be the cause? any feedback is appreciated!