The fuel FILTER could be plugged up a bit ! Get a new Delco filter installed and see how the Impala responds then. It is located forward of the driver'* rear wheel on frame.

gibberish: unintelligible or meaningless speech or writing; nonsense.

I believe this was directly in reference to your statement in Post #13 where you tell us that a certified GM technician says you said something. Telling us that someone said that you said something is meaningless. This makes "gibberish" an accurate definition.

Since you are an ASE Master Certified Technician, you know that many things can cause this kind of behavior, hence the following questions:

As stated by others. Fuel psi spec is 52-59 psi. At 28 psi the engine won't start. Make sure the fuel filter in not restricted. Some times after sitting the "crud" in the filter relaxes and allows enough fuel flow and restricts as it runs. Also you can restrict the fuel return to make sure the regulator isn't an issue.

Do you not understand that when fuel pressure gets low, it causes symptoms such as the ones you are complaining about? An engine WILL start when the fuel pressure is at the MINIMUM starting pressure of say 50psi. Some engine can start at a lower pressure, but not always. An engine WILL continue to run at a LOWER psi, but WILL run like **** because of the lack of fuel flow. Hence sluggish going uphill etc. So again, when you replace the pump, quite certain you will not see this issue again.

So, the idle air control valve in the vehicle was always a problem, and I've had to clean it out and the orifice as well twice, so I went ahead and replaced it and when I replaced that we had a problem with the EGR valve. After replacing both of those parts the car was no longer sluggish up hills and ran great for 3 days. Then after that, the car became sluggish up hills, and the car would continue running as long as you did not shut it off. When the car was hot after running while it would not restart. I put the Autel on the car and found that the fuel pump for some reason is losing pressure due to running too hot which is usually indicative of a soon to be completely shorted out pump coil. I watch the fuel pressure as the engine ran longer and longer going down and down until it reached about 38 PSI. If anybody knows why a 3.4 would just not restart after being run for a while oh, and being sluggish up hills which is indicative of a bad fuel delivery oh, and the reason I say a fuel delivery is because it is not a ignition coil pack problem. And ignition coil on these cars, hit and miss or it'* a misfire when you step on the gas, in other words introducing a load, and that is not the issue I can step on the gas but it does not jerk, however it does not Step Up oh, it'* just sluggish. If anybody has any ideas let me know!

Holy **** dude, we just ******* told you. Fix the fuel pump and MOVE ON!

@CathedralClub if he continues to beat around the bush, close the thread.

HetzC22: Here I am typing Post #28 after many folks have attempted to assist, while you appear to be ignoring all of our advice while not answering some key questions. We like to help folks, but since we do it for free, we don't like to waste time. Answer some questions and/or act on some advice, or we will likely lose interest. I could leave the thread open forever, but since it is going nowhere and wasting everybody'* time I will close it if your next response doesn't indicate some progress or give some answers. I will do this just to keep folks here from being tempted to waste even more time trying to help where it appears impossible. Others can use our time and advice productively.

Your move . . .