2001 Pontiac Grand Prix Hesitation/Problem Shifting

105,000 MILES • 6 CYL • FWD • AUTOMATIC
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ALONCZAK
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  • 1 POST
My car has recently been hesitating and surging during acceleration. It also has been having trouble shifting late or downshifting. When it needs to downshift the RPMs will rev but nothing happens. I took it to a transmission shop and found that my transmission pan was badly damaged and also found that two fluid lines were damaged inside the transmission. This was all fixed and the transmission was given a clean bill of health. However, my check engine light just came on and the same symptoms are continuing. The codes on the diagnostics call for a misfire/catalytic inefficiency. Any ideas on what this could be? I heard anything from wires/plugs, oxygen sensor, catalytic converter and so on?
Dec 2, 2008 at 11:59 AM
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SERVICE WRITER
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2 codes?
What are they?

po300 and po420?


Also, how many times has the filter and fluid been changed in the transmission? What does the fluid look like now?
Dec 2, 2008 at 12:03 PM
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