blew a headgasket last friday so i changed the head gasket and valve cover gasket now its all back together and i cant get it to stay runnin??? itll start up and run for maybe 5-10 secs then start stumblin real bad and then cut off. Itll start back up but it the idle is all messed up and it just cuts off. im a lil lost because everything is how its sposed to b ??? any ideas