I have a 1996 K1500 we just put a new Vortec 5.7 in it. We have replaced almost all sensors. Truck ran fine the first few days now it idles really rough to the point not sure if its going to die. When you drive down the rode it hiccups to the point it feels like you are driving on rumble strips, then it will level out and ride fine then when you reduce speed or try to gain speed it starts running rough again. when you are going slower or having to stop for traffic it feels like it is going to die. Have hooked it up to the scan tool and only code we get is about the EGR.