There are several things that determine when the trans shifts. If the cat goes bad you should get a rear O2 sensor code, you had a front O2 sensor code. Seeing that you have a code that needs to be taken care of before anything else. Don't see how the EGR would effect shifting. I don't even have a EGR on my car. The problem I mentioned wont show up on a scan, the trans would be fine. It'* in the PCM that the problem likely lis. Shifting is triggered by RPM and MPH. So lets say you have higher gears now then what you had, you would reach the RPM first. Then the PCM will try to get the MPH to where it should be but hit'* the rev limiter. I still think the problem is in he new transmission being different then your old one.
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1997,1998,2000,2005 year confused Bonneville SSExi. Stock? ish.
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