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Discussion Starter · #1 ·
FNG here, I recently picked up on 02 Z71 (5.3, NP246), and took it for its first longer drive the other day (3.5 hours each way). While driving on the interstate, if I let off the gas and/or tapped the brakes, the engine would instantly drop to idle and I got a loud whirring/spinning noise from the trans. If I blipped the throttle the noise would stop and engine RPM would come back up. The problem didn't happen if I had cruise set and cruise was slowing the truck down on a hill (I'm guessing that cruise always keeps the throttle partially open).

Now, this didn't happen every time during my drive, it started about 2.5 hours into my trip out, and again about 2.5 hours into my trip home. This has never happened in the 2 months I've had the truck, but again, I've never driven it more than about 2 hours at a time. This makes me think it is heat related somehow, but I'm not sure why.

I've read some about the TPS going bad and causing the torque converter to act up, but haven't read anything about the noise from the trans. Is it possible that my TPS is getting heat soaked on the longer drives and causing problems? Any other things I should look at before blindly throwing money at the problem?

I did notice that the ATF is reading overfilled on the dipstick, but someone stripped the drain plug, so I haven't drained any fluid out yet until I find the time to undo the cooler return line and dump some there. Its not overfilled to the point of puking fluid out.
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