I have a 2005 chevy avalanche 5.3L 4wheel drive. The vehicle starts and runs good and you wouldn't think anything was wrong with it while driving. That is until you step on it. If I were to spin my tires from a standstill in the snow and get the engine revving a bit then let off, the engine continues revving for a couple more seconds after releasing the pedal. If I were at a stop on pavement and step on it hard the engine falls flat pauses then slowly picks up speed. If I were to do a rolling stop then proceed and try stepping hard on the gas it picks up speed kind of sluggish. If on the highway and I were to pass, the engine will kick in but only briefly then picks up kind of sluggish. I had replaced my fuel pump due to it not holding pressure. I have replaced my throttle body with throttle position sensor, as well as the pedal position sensor.While changing the throttle body I did find what looked like oil contaminated by water in the little passageway that goes through throttle body to the intake manifold to inside the valve cover. I don't know what that passageway is. I picked up a scan tool that has live data, only I am unfamiliar on using this tool still. Any ideas on what to look for while doing a drive test with live data. Both a code reader and scan tool does not read anything and the there is no light on.