Interesting. I am experiencing the same problem. Now for me, I have had my car since it first hit 2 miles on the clock back in 2003.
And I have also gone through 2 engines in the car.
But now that I think about it, I have not changed out my IMRC. (Moved over from engine to engine) That does sound like something that would be stopping the acceleration.
Good suggestion, NJSVTGUY.