98hooligan

whats happening guys. im new to these forums but i have visited plenty of times regarding help with my jeep. ive got a 98 cherokee with the basics. 5.5in lift, 33s, header, cat, wheel spacers, 4.0l aw4 tranny, 180k, and alot more just basic stuff. recently my jeep has start missing out and spitting and sputtering when first started. ill start it up and it will run fine for 30 seconds or so and then start going nuts and start running REALLY rough. this only lasts for about 45 seconds or so and then quits and runs fine and you could run it all day and never have a problem out of it? i did a basic tune up (plugs wires cap rotor plugs) thinking that might be the problem because it looked like it had never been touched and didn't help a thing but does run better when driving. anyone had this same problem or know what the problem might be or how to fix? its driving me insane. no codes are showing and check engine light isnt on either. any help would be appreciated guys! thanks!

XJ Stryker

Clean you intake and a tune up should be done on any old vehicle u buy to start your own service record. I would change ALL fluids too

98hooligan

thanks and i have replaced everything except the diff fluid