thanks for the help turned out it was my cat converter. The damn thing was falling apart inside. the way i found out was i removed my o2 sensor to get a replacement. after i took it out i started it up and the thing revved up, drive down the street with no problems. then i put the sensor back in and back to it's old self.
so i had and extra cat and muffler from a 99 xj. after some welding and cutting i've finally got to feel the power of my 4.0 for the first time. again thanks for help
lee