Suzuki: vitara v6, fuel mixture, 3000rpm

Question
hi ive got a 2ltr v6 lwb vit my problem is after about 10 mins of driving i get a hesitation @ about 3000rpm then as long as i keep it above 3k its got all its power but if i go below its does tha same now if i turn engine off for a couple of secs it clears tha problem again for about 5 mins then it returns so far i ahve changes changed plugs coils and fuel filter but no difference
any help greatfullly received
thanx simon

Answer
Usually, a hesitation is caused by a fuel mixture issue.  What about Oxy sensor, and the other electronics?  It would be interesting to see how much and in which direction the injection is attempting to correct the mixture.  (long term fuel trim)
scotty