Hi,

The most likely cause is supposed to be the fuel pressure regulator as it is made to stop returning excess fuel to the tank under accelerations.
A vacuum and its port from the intake manifold is the trigger mechanism for it to work.
You might have a plugged up port source. Easy enough to check out before getting all warm and fuzzy with pressure gauges. 🤭

If it’s not starting hard from the lack of rest pressure inside the fuel rail or acting like its flooding, then the FPR is most likely OK.

The next thing could be a CPS starting to go wonky as it affects the timing but then your idea of a bad throttle switch that tells the ECU what you are wanting to do next is a good start in the proper direction.
The TPS has to show a change of state each time it moves. Idling to off idle and to wide open throttle.
The END between zone is left to the FPR’s calibration.

The vacuum at idle works in conjunction against a preset spring pressure and the incoming fuel pressure to open the valve seat upon starting. Otherwise it should stay shut.
At idle it is there to return some fuel to the tank.

When less vacuum occurs, then the valve, that was partially open, is adjusted to completely shut down and the fuel backs up on the rail side.
Then the injectors have more fuel volume to spray with.

The ECU controls the time open and is known as “pulse width.”
Its uses the O2 sensor signal to adjust mixtures and a RPM signal to set the timing advance sooner to get the burning going sooner as RPM increases.

The ignition systems only work so fast to get sparks there soon enough!
The spark from an ignition coil is only “X” long in duration too.
So, from some beginning point, the rest of the added fuel is supposed to all burn up. 🤫
But we know that never truly happens or we wouldn’t need catalytic converters. 🤔
Yes you get more power only because you cram in more cycles per second and forget about those left overs doing any more than they could do before!
You can smell a mismanaged engine on any grade right away but unless you are behind your own car you’ll never know. Isn’t that beautiful about combustion engines even at 35,000 feet.🙄
I hope they are more sophisticated up there than down here!

Have you got the spark plugs clean and gapped correctly? As that can be somewhat critical on the red blocks believe it or not.

Yep you will have to think through what you feel and can find to iron the wrinkles out of this one, especially if it’s intermittent.
😬

Keep us entertained!

Phil