04 silverado Spudder

My 2004, 5.3L, 4x4 spudders when ideling or stoped at a light.Also running the idle up you can feel it till 1700rpm, driving down the roadit goes away. Had at the dealer three times, said couldn't find any codes but they
can feel the spudder. Checked everything, furl pressure, compresion, injectors. Said they checked out fine and that the only way to find out what it is is to waite for it to quit running. Another respected mecanic said to have it put on an engen anlizer, that will tell you what the diagnostic wont. Another thing is after you start it and take off when the engen is cold you can feel a clunk in the gas pedel when it goes from first to second gear. Any Info Thanks Craig.
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I'd say the clunk in the gas pedal is a bad motor or trans mount:
Most likely the trans mount. As far as to wait for it to quit running, ask for a loaner car and let the manager drive it till he gets stranded!
I'd go with the five gas analyzer for a test drive, my bet is on a leaky injector, or even a partially stuck EGR Valve.
A leaky injector can cause a very rough idle, sometimes a tooth chattering vibration. It might show up on a fuel pressure leak down test, or it may not, sometimes it will only leak dynamically under driving conditions, so that's where the portable five-gas exhaust analyzer comes in. That will show a leaky injector or even a sticking EGR Valve.
I hope this helps?
Refinish King

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Whur did yu lern to spel?
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