99 silverado 5.3L reving up and down

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99 silverado 5.3L reving up and down

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Chevrolet Forum >> Chevy Trucks, Vans & SUV's >> Silverado >> 99 silverado 5.3L reving up and down

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99 silverado 5.3L reving up and down - 2/23/2008 9:12:12 PM

ctaylor71803

Posts: 1
Joined: 2/23/2008
Status: offline

I have a 99 silverado z71 with the 5.3L, it has 153,000 miles on it. Since it's had around 110,000, during the winter (cold) the truck sits and revs itself up and down up and down 500rpm-1500rpm some times up to 3500rpm. I have changed MAS, plugs and plug wires, new fuel pump. The truck does not do this in the summer time just when its cold, I'm sure it's a sensor but not sure. can anyone help?

< Message edited by ctaylor71803 -- 2/23/2008 9:14:06 PM >