Problem with electronic throttle control

Buy a can of electrical switch cleaner and spray both the male and female connectors on all those items involved.

If that doesn't fix it, you need an auto electrician with a pro grade scan tool computer who can scan for communication issues and record the Live Data as it happens and what made the electronic throttle indicator light come on.

https://dashboardsymbols.com/2010/11/electronic-throttle-control/
Electronic Throttle Control Indicator This is the Electronic Throttle Control (ETC) Indicator symbol. This light, a lightning bolt between reversed brackets or parenthesis, will illuminate if there is a problem in the electronic throttle control system. As an electronic system, it can sometimes be reset with a restart.

it appears you have electronic throttle control. any applicable trouble codes, relating to that system? clean the throttle bore and around throttle plate, don't force the throttle plate. your idle air is electronically controlled.

reduced engine power has to do with the electronic throttle control or drive by wire . All electronic wires under the dash on the gas pedal , electric motor on the throttle body . DTC'S - diagnostic trouble codes stored in the computer . Take it to the dealer .

Engine stalls cold or RPM fluctuates at idle up and down or dies near idle.

This problem is commonly caused by a dirty automatic idle speed control valve and throttle valve but always run a OBD2 fault code as well as the cleaning procedure. Buy a can of throttle valve cleaner (do not use carburetor spray cleaner!) from NAPA or Carquest (made by CRC chemicals) and spray it into the air intake while the engine is running, use up about 1/2 the can, engine will try to stall hold the speed up, shut it down and let it soak for 30 minutes, restart and blow out the remaining fluid, shut it down and disconnect the negative battery cable for 5 Min's to reset the base idle control. If the above cleaning doesn't cure your issues you need to have the computer controlled automatic idle speed control system diagnosed and repaired by a dealer or electronic engine control repair shop.

While I agree that the fuel pump would be the most likely suspect for this car failing to restart, if it is the fuel pump, however, the fact that it started after tapping hard on the throttle would be pure coincidence.
I believe that all e46s have used drive-by-wire throttles. That is - there is no throttle cable between the gas pedal and the throttle. The gas pedal generates an electronic signal that tells the computer where your foot is, and the computer opens the throttle. You say that the car experienced a sudden stop. Did the engine get shut off while the throttle was open? If so, perhaps flooring the throttle caused the electronically controlled throttle to cycle and reset itself (just a theory).
Listen for the hum of the fuel pump when you turn the key to the On position, before you turn the key to the crank position. The hum should last only a second or so. The pump shuts off after the system is pressurized. If you don't hear that hum when the car fails to start (if this happens again), then you have a fuel pump problem.

I don't see the knock sensor on the 4.0L engine. --- COMPONENT LOCATIONS Fig. 1: Electronic engine control component locations - 2.5L engine shown
Fig. 2: Overhead view of the (A) automatic idle speed motor, (B) MAP sensor, (C) crankshaft position sensor wiring harness, (D) air temperature sensor, and (E) throttle position sensor - 1992 Cherokee with the 4.0L engine shown
Fig. 3: Electronic engine control component locations - 4.0L engine shown
Fig. 4: Electronic engine control component locations - 5.2L and 5.9L engines (Part 1 of 2)
Fig. 5: Electronic engine control component locations - 5.2L and 5.9L engines (Part 2 of 2)

We have been experiencing same faults on a 2005 Expedition,with engine stopping and the message "Check electronic throttle". Ifirst went to AutoZone and they read the codes. They suggested replacing thethrottle sensor, which we did, but car stopped again. We had to replace thebattery in a month and this is the fix. The battery was almost 6 years old andwhen you first start your engine, it sucks too much load and gives these faultsto the computer. It never stopped since then (3 mo already). Sometimes we useto get the message 3 times a day.

they do have an idle control system on throttle body.. make sure no vacumm leaks...... also try changing the ect two wire electronic cooling temperature sensor....common honda problem use oem... let me know for further

i believe i have the same problem believe could be the electronic control throttle unit wihch controls you speed control on your car, acceleration but when you put it in drive it fails to go and it kicks off. it not official yet but my mechanic is telling me we start frim there,

Most likely a dirty idle speed control system follow the guidelines below to clean it.

Throttle Body Cleaning on vehicles without electronic throttle control (most 2003 and down)

You can in most cases repair this slow speed stall or unstable idle by cleaning the engine throttle valve and the idle speed control valve using a product called CRC Spray Throttle valve cleaner. Spray the cleaner into the air intake of the engine with the hose removed from the throttle body, the engine will try to stall so hold up the idle speed manually. Once you have used up about 1/2 can of the cleaner stall the engine out while spraying and turn the key off, disconnect the negative battery cable for 5 minutes and then reconnect and drive the car for a about 25 miles of varied driving modes. If this doesn't cure the problem you may need the fuel injectors professionally cleaned by the dealer service dept.