sometimes when im driving and come up to a light the rpm drop below 250 for a second you can feel it get rough then goes back to about 600 rpm..any thoughts..also when i shift sometimes it does the same thing ive already replaced the iac and cleaned the throttle body really good,plugs,wires,rotor and cap and still nothing

 

It could be different things. Check and see if you might have any codes stored. Here's how to check it yourself. >-> http://jeephorizons.com/phpbb/viewtopic.php?t=2719
I check my '97 ZJ's codes all the time just out of curiosity. Recently I found a cylinder misfire that I hadn't even noticed. Replaced the plugs, cap, and rotor, and all is fine now.
Dan

 

checked its only the norm 12 because i just redid my radio and disconnected my batt and 55

 

Well the 4.0L has issue that I'm not real familiar with being as I've never owned one. Maybe someone will chime in with some helpful info here.
Dan

 

Can you have it scanned for codes....I'm thinking trans codes related to a failing torque convertor clutch solenoid..TCC. When they start to fail this is one of the sysptoms....has it ever stalled at a light?

Also a sticking 3-2 shift solenoid could cause it.

 

it only stalled when i had the bad iac and it only does it every once in a while...iver read the fuel pump could effect his because of a drop in pressure and i have to change mine anyway because of a failed check valve and a leaky gas tank.

 

Oh.........didn't know about that........only going by what you posted