rxneix

Bought an 07 IS250 about 8 months ago, no issues until now, have around 172k miles, put on around 20k since purchase. I have run into an issue when accelerating, will be driving normally and then my RPMs will drop about 500-1000rpm, the accelerator will stop working(total loss of power) IF I keep my foot on the pedal, however the moment I take my foot off the pedal and start accelerating again, I receive power and it starts to drive normally until the pedal decides to stops giving power, to which I do the same thing to get power. Sometimes this happens when I am at low speed, sometimes it happens when I am on the highway, but I mostly notice it after I have come to a full stop and start accelerating on an entrance ramp. This issue is also more noticeable on colder days, or when the engine has just started. Other than that there is nothing abnormal about the drivability, I recently changed the spark plugs and ignition coils assuming that was the issue and no change has been made. I brought it to a shop they said my intake was loose and improperly installed the last time the spark plugs were changed(this was prior to me changing the spark plugs out), and reinstalling the intake didn't solve the issue. They also said they didn't notice the hesitation problem when on the diagnostic test drive. My buddy thinks it could be a shift solenoid or potentially a fault ECM. I have no CEL on the dash so I have a feeling it could be a clogged fuel filter, or a faulty MAF. I have considered taking it into the dealership to have a full inspection done, but that seems pricey. Most repairs are done by me or my buddy, so we have been attempting to locate the problem with no luck. I am curious if anyone else has had a similar issue or if y'all have any advice on how to properly diagnose the issue, so far I haven't seen too much on this specific issue for the IS250.

MoonBase

When my 06 is350 gets weird pedal feel, it means I need to clean the MAF. Simple and cheap, one can of MAF cleaner lasts a long while. I typically do it once every oil change at this point just to keep the crispy pedal feeling. Might look into fuel system. Could be a good idea to run your VIN through the lexus recall database and see if any of the old recalls are something to worry about. (https://www.lexus.com/drivers/service/warranty-recalls)
I'd vote with looking into the simpler and cheaper options first, unless you manage to narrow it down more.
Does the loss of power happen in the middle of a gear or during a shift point?