The car is 1995. Only 3 items are OBDII, among them emissions/catalytic converter, the rest is all OBD.
So I drove up to New Hampshire where jag-lovers user John6 has a PDU, that can read this data. it/s a monster of a computer, but he was able to check the Throttle data, and it only showed 33% with fully depressed pedal. We traced it around the engine, and found the culprit, a loose throttle cable due to a broken plastic piece right where it comes off the Traction Control Unit, mounted at the passenger side to the right where the fuseboxes are, near the firewall. We temporarily stabilized the broken plastic with wire and duct tape and that was it. Wow.
(The PDU also showed that the ABS front sensors were out, and that seems due to broken off ground wires at the wheels.)
What a different driving experience with 100% throttle!
Reg the S/C: I had bought a used one from Ebay for $500, but it makes a roaring noise when the car is cold. So I am having my original one rebuilt by Magnum Powers in Oregon (recommended somewhere here), and then swapping it back in.
Thanks for all the feedback!