OBD1 is really basic, if it's a minor problem like missing it won't
tell you anything.
The TPS part is what is baffling me, because you tested it, of coarse you
checked it for the proper position when you did that, or did you pull it out
of the throttle body? I had a problem on my trucklet, long ago, was the
plug wires, they just needed new ones, was a sort of miss driving down
the freeway, felt like fuel because it would sort of stumble, then pick up
and run OK, but would repeat over and over, but at no predictable interval.
What happens when the spark drops off is the O2 sensor reads unburned
intake charge as lean, even tho if it were to have lit in the cylinder it would
of been a perfect mixture, so the computer goes to work enriching the fuel
mixture and that can lead to more miss fires and more enriching, it's a compounding
circle effect.
Have you done the plugs and wires? even checking for the correct gap? cleaning
and wires might be all that's wrong, and seeing you have ruled out all the hard stuff
that might be causing the computer to make it run bad, this might be it.
Also one last thought, oil or water down in the spark plug holes on a 16V could
be causing miss fires from grounding to the head
Wild