Rpms have been very erratic?

2007 CHEVROLET IMPALA
147,200 MILES • 3.5L • AUTOMATIC
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BSM1984
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My rpms have been very erratic. I barely press on the gas and it's going to 3000 rpms. It's gotten worse especially after at stop signs and red lights.
Just had an oil change and serpentine belt replaced this past Monday. I had more transmission fluid added in June no leaks from that. Also my gas mileage has gotten worse. It did give me a p0700 code today that's the first time
Aug 22, 2026 at 8:31 AM
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JACOBANDNICKOLAS
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Hi:

When you say the RPMs have been erratic, do you notice it when accelerating or when the vehicle is sitting idle?

I ask because the code you have, P0700, is related to the transmission. This diagnostic trouble code (DTC) indicates the transmission control module (TCM) has set an emission-related transmission DTC. The engine control module (ECM) receives the TCM information over the serial data circuit. The ECM illuminates the malfunction indicator lamp (MIL) when the TCM sends a message over the serial data circuit requesting MIL illumination. The DTC information for the ECM will only display DTC P0700, but the freeze frame/failure records data may display the transmission DTC that was set.

Do you have access to a scan tool that can read freeze frame info and codes other than engine codes?

Let me know.

Joe
Aug 22, 2026 at 7:31 PM
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BSM1984
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At idle at one point it was going between 500 to 1000 rpm. I just have a standard obd2 scanner.
Aug 22, 2026 at 7:45 PM
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STRAILER
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Is the transmission fluid full? I would check that first.
Aug 24, 2026 at 5:22 PM
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BSM1984
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Yeah I took it too a shop today. The transmission cooler lines gave up. The clutch pack was fried so quoted $6800 for a new transmission
Aug 24, 2026 at 5:27 PM
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STRAILER
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Hmm, sorry about that, it happens, you might want to try a used transmission so save money. Low miles from ebay?
Aug 25, 2026 at 6:55 AM
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BSM1984
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Yeah the repair shop it's at won't let me do that I even asked because I found one totally rebuilt with the torque converter. And it was $2000 less then there quote
Aug 25, 2026 at 7:06 AM
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STRAILER
  • ✓Experienced Mechanic
  • 55,319 POSTS
Yep, some shops wont do want you want them too, you might want to shop around.
Aug 25, 2026 at 7:50 AM
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