94 pathfinder starts to sputter at operating temp
 

I'am new to the site hope someone can help me.Iwent through all the threads but could not find anyting close to my problem.I bought a 94 2 wd pathfinder for my daughter. Put new plugs ,dist. cap ,rotor button,radiator.It starts to sputter after reaching operating temp, does fine till it gets to that point.thought it might be the catilitc converter , talk to several shops they don't think thats it. I'll take any advice anyone can give.thanks in advance