1988 Rough idle.

Hello, so my 88 xk is having some idling problems and i'm starting to beat my head against the wall. So before winter i tuned it up, plug, cap, rotor, and fuel injector cleaning done. Drove it about 150 miles and parkrd it. Got it out late this summer, and is idling rough once it warms up. I have run two tanks of fuel through it, re checked the plugs, replaced wires, had all 12 injectors rebuilt, retimed it, new cap, found intake leak and fixed. I think i have checked everything ican think of. the rough idle feels like a miss but donest happen all the time, but is enough that i feel it sitting at a stop light. car has 25,500miles. Any help would be great.
Thanks Tim

Also found the plugs are black from idleing. seems tobe running rich, should note found the car will not start if coolant sensor is unpluged or will die once unplugged. omhed out at 347komhs @73degrees C.