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05 Impala running issues

To be honest I’m not sure if they replaced it or not but they went through the whole thing. It’s not kicking like a transmition engagement issue. Also happens at 60+ mph and not kicking when shifting

I thought of the torque converter too when reading the OP, like Barky above. I’m thinking some kind of problem with the lock up mode. Often the lock up mode can be temporarily disabled by unplugging a connector. Might be worth a try anyway.

You say the engine is overheating? At what times? Freeway speeds, or at stop & go & idling? If it is freeway speed overheating, you could have something causing a lean air/fuel mixture for some reason. Faulty MAF or O2 sensor or air leak maybe. Look carefully at the boot that leads to where the MAF is located, make sure it is in place, sealed, and intact. The stalling out might just be the effects of the overheating. What does the does coolant temp gauge say when it is overheating? Pegged all the way to hot, or just slightly hotter than midway?

If it was a plugged cat problem, it should be possible to diagnose that by an exhaust back-pressure test. there should only be 3 or 4 psi cat back pressure. If you got 10 psi, that would probably mean a plugged cat. Or just driving the car with the cat removed temporarily, see if the problem goes away. Sometimes posters here say you can just remove the pre-cat O2 sensor as a way to temporarily bypass the cat. Wear ear protection, very loud.

No the engine is not overheating, sorry for the confusion, just gets abnormally hot under the car. My next step is to try and remove the o2 sensor before the cat and see if that helps

A failing catalytic convertor can cause this.

99 TSBs on the '05 Impala, 5 recalls. None for this exact issue. There are two related to “Ticking or Knock Noise” TSB #03112005 and TSB #3692 which also has an addendum. Cracked or broken flexplate is the description. Good luck. Here is a complete list of all the TSBs in case you want to review them more closely. They are separated by major system.

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