I had an intermittent hesitation under load on my 86 3.2.
I replaced all same crap and more
It ended up being the fuel injection wiring harness!
The factory folded the harness back on itself and stuffed it into a clamp, over the years the insulation broke down.
At idle, reach deep into the engine bay and pull/push the harness around, if the engine stumbles - you found it!
BTW the most conclusive vacuum leak test was a smoke test. I tried them all.
Good luck