2002 grand prix rpm goes up and down when ruuning idle and car uses twice as nuch gas replaced tps problem still exists
sounds like you might have a vacuum leak, could cause the idle problem. also an idle air control valve could do it. a vac leak could also cause more fuel consumption. also when was your last tune up? your last air filter?, fuel filter? Scan the computer for codes also. with the engine running like that there should be a code stored.
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