Try to block all the air that goes through throttle body (including IAC inlet). If the engine does not stop, then you have an air leak somewhere. Also, make sure the bolts are tight on intake/exhaust manifold. Could be a leaking intake/exhaust manifold gasket as well.
98 TJ 4.7 Stroker!!! Unichip tuner, HPD30/D44, 4.56, Detroit Locker in rear axle, 3.25RC SL, 1.25BL, 1MML, 35x12.50x15, Cager Softs 15x8, XRC10 winch, Rancho 9000XL shocks with wireless remote