[huey224]

I have a 03 windstar i just bought has 156000 miles on it and it starts fine but it idles good but u can hear a slight miss dont show up on tachometer or throw check engine light. while u drive it surges not really bucks and once again dont show up on tach but u can feel it. i changed the fuel filter and air filter and pvc valve is good put full tank of fuel with injector cleaner and still doing it. any suggestions would b good ive heard some people say check intake gaskets? do they mean upper plenum? thanks any info will help also i havent checked plugs or wires yet but i am 2morrow