AJAR door lights stays on. Even when the door is closed (really really closed). Suspect passenger or drivers side door, not trunk or deck-lid or whatever you call it.

I think it is some kind of sensor, I am not sure. Where is(are) the door sensor located?
What is triggering the AJAR light?

It stays on all the time, also with driving, and door etc firmly closed.

the doors use "jam" switches. located between or around door hinges.

The Trunk or hood switches are more prone to problems from my experience.
Doug Venner NJ
85 GT, 86 SE, 86 GT, 87 SE

The ajar switches for 84-86 are on the door frame at the rear of the door, above the 'striker bolt'?. -- push switches. For 87-88 they are attached to the door latch mechanism, inside the door.

The pin switches in the front pillars, near the hinges, are for courtesy lights.

Usually when this happened to me, it meant that water had seeped inside the pin switch for the front hood at the base of the windshield.

Alternately, it's possible that the small black plastic tab broke off in your decklid latch and so even though the latch is closing properly, the tab isn't able to disconnect the light circuit when the decklid is closed like it is supposed to.