2002 e150 v6

What would cause my van to run rough. I replaced the spark plugs and wires thinking that one or both of these could cause this. It didn’t help. The engine runs rough and sometimes “bucks” after going through the gears. (It’s an automatic) The odomether says it has 200,000 miles on it but you wouldn’t be able to tell it just to listen to the engine at an idle. Also, it doesn’t cut out when accelerating. Just when you take a load off of the engine, (coasting). Any suggestions? Could it be the coil pack ? Maybe a vaccum leak? Sure could use some help.



Thanks.