if i start it with out giving it gas it wants to die it revs to less then 600rpms and dies, it sounds like it wants to run be just cant. if i give it gas for a few sec then let off it will drop down to 500rmps then hesitates up to like 700 then it idles, if its idleing and i give it a little gas quick (rev to 1800 ) it will go down to 500 then hesitates back to 700. what could cause this? what dose it sound like?