Please HELP! Weird startup problem
 

Hi guys, ive been experiencing a strange problem intermittently when i start up my 2004 accord coupehttp://images.intellitxt.com/ast/adTypes/2_bing.gif 2.4 litre with an auto trans. When i startup it seems as if the engine is misfiring or only half the cylinders have ignited and the front of the car shakes and the idle is very low from usually in the 1500's to the low 500's. Now if hit the accelerator the engine returns to normal and is fine for the rest of the day. I just had the spark plugs replaced and the starter changed, which was going bad. Can anyone please tell me what might cause this issue.