2000 Silverado with high idle

2000 Silverado LT, automatic, that just had the rear end replaced and a new battery installed. Whether warm or cold once I get moving it appears like the idle is high. If I come to a stop sign you can hear
the engine higher then normal and slight pressure on the brakes to keep going. Sometimes when I release the brakes I hear a clunk as if they were pressured and the truck moves on. When accelerating from a stop I can reach 2000 RPM or so and it will almost hang there for a second or two then change gears, same at next gear. That is the only way I can describe it but i'm looking for advice before I go back to garage to discuss it with them. Not sure if its noteworthy but when changing the battery they somehow put a surge through the truck as they blew the fuses and a resistor in the autostart module, and blew the fuses in my pioneer stereo.
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On Thu, 10 Sep 2009 05:33:20 -0700, Sibernewf fired up the etcha-a-sketch and scratched out:

Just a guess, but did the idle issue occur before the battery? If not, you may have blown out your computer as well. That could cause inconsistent O2 readings, which would force the system to run rich or lean or both depending on the moment.
If it is running rich, you might look into the injectors or cat.
You could also check for a clogged EGR valve.
What do you have - the 4.3L V6, 4.8 or the 5.3 V8 model or the 2500 with the 6.0?
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5.3 V8. Garage is going to put it on some kind of system Monday morning so will see then I guess
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On Fri, 11 Sep 2009 10:36:33 -0700, Sibernewf fired up the etcha-a-sketch and scratched out:

I was just going to suggest running some Seafoam through it first. Google around and you'll see how to add seafoam to the engine. It will clear out your injectors for a start.
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PerfectReign wrote:

First thing I would suggest is to disconnect the battery. let it set for 20-30 minutes and reconnect. I have seen more than one vehicle seem to lose the initial settings from a power spike.
Next would be to make SURE ALL the fuses are OK. Then check for a loose vacuum line on the rear of the engine. Then throw a scan tool on it and see what it is seeing from the ECM.
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Throttle Sensor was on the fritz. New one in and back in action. Curious though if the surge from last week blew it or did it go on its own..
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