I'm having similar (though not as bad) idle problem. I think mine is due to the TB adjustment needing to be pulled down. I'm idling at probably 1400-1500RPMs, not anywhere near the 2800 you're experiencing.
Denis A. Baldwin
1991 YJ 2.5L, 1" BD MML, 14 Bolt Rear, Dana 60 Front, 5.13 Gears, Detroit Lockers, 37ss, Cherokee Offset Springs (10" front to back stretch total), Bilstein 5150s, 1in. BL, custom cage, Warn M8000, Double D Dash/OHC, 4Low Front Stinger Bumper, DirtWorx Rear Bumper WTC, Tube Fenders, Comp Cut, 1 Ton HD Kingpin High Steering and PAID FOR.