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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.

  • Welcome to Motor Vehicle Maintenance & Repair! How many miles are on your Avalanche? If it's anything like my '06 Silvy, I'm encroaching upon 200k. What have you done for tune up on it? – Pᴀᴜʟsᴛᴇʀ2 Jan 15 at 17:16
  • The plugs were put in last summer. Recent MSD plug wires, new map sensor, new maf sensor, new air filter, the fuel pump was replaced which has the filter and pressure regulator on it, and a new throttle body. – rodger Jan 17 at 13:38
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    How did you go about calibrating your throttle position sensor? – Pᴀᴜʟsᴛᴇʀ2 Jan 17 at 14:29
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    You should always calibrate your TPS. No two are exactly the same (or should be treated that way, anyway). I've not done it on my SIlvy (my truck is fly by wire, which doesn't have or need a TPS - it's built into the servo) so not sure (not done it on an LSx either). If there is a mismatch between where your throttle is at and what the TPS is telling the computer, it could cause the situation you're talking about in your question. – Pᴀᴜʟsᴛᴇʀ2 Jan 17 at 15:29
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    Like I said, the TPS is built into the servo for FBW setups. I'd bet your truck should be FBC, as most '05's were. (If I'm wrong on that, no big deal). If you did the relearn, that's actually what I'm talking about. You may try doing the relearn again. That the engine is not responding to me is a good sign there is a mismatch between what the throttle is doing and what the computer believes it should be doing. But, that's just a starting point. – Pᴀᴜʟsᴛᴇʀ2 Jan 17 at 16:00

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