99 explorer rough ridle and ride

I posted a message last night about a pinging noise that I heard coming from my engine bay. Today while driving I noticed that at stop lights it feels like it is going to stop ever once in a while. The RPM's drop and it feels very rough. I have noticed this while driving too, everyonce in a while it will bump a little bit, at first I though it was the transmission but it does it at idle also and it doesnt jump or make any noises when it is changing gears.