I have an 87 300e The car will some times start hard when it is warm. It will miss and sputter, then clear out and run fine. It has new plugs, the cap and rotor are in good shape, and I put a new fuel filter on and this has changed nothing. I think It could be the idle controll valve, because it dosn't happen all the time, and only when it's warm. How do you check the valve is my frist question and what else could it be? Where should I look next

Thanks guy's