I have a 94' Z71 5.7 liter I have replaced the PVC valve, engine temp sensor, air filter, oil change, and just did the cap and rotor. Truck idles at 800 rpm but shutters as if it was misfiring slightly or fuel problem. When you bump the throttle in park it bogs out until rpm goes above a 1000. Then fine??? And it runs excellent under heavy throttle???? I need to be specific if I ease into bumping theottle in park its fine but just bumping throttle it lugs out just for a second, don't do that before I did cap and rotor? But always had the rough idle or shutter I should say? Because the rpm needle never leaves 800rpm at an idle? Please help!!!

 

Have you tested your throttle position sensor?

Have you tried cleaning your throttle body?