Still trouble with 94 four runner

I’ve got a 94 runner 3.0 v6 5 spd 4wd, that runs great at idle, great at highway rpm but stutters a bit at mid range under a light load. i.e. very unsmooth accel from 1200-2600 rpm. like accelerating in 2nd gear after turning a neiborhood corner. Lots of people have looked at it and no solutions. It is worse with A/C on (additional load). Tested air mass meter, it’s fine. Replaced fuel filter, no help,timing and advance, right on the money. blood pressure, rising. Thanks for any insight!

There are 2 things I would consider. One is a fault in the EGR system. You might try plugging off the vacuum line to it and note if the problem disappears then.
The other could be a corroded end on a spark plug or coil wire, which can cause an unusual stutter at odd times.
That may not be much help, but…