Recently my XG300 has started to have a very prolonged 'hesitation' @ 3000
rpm & above. It had been running perfectly & there are no stored codes. If
you drive it gently, you really think it's fine. But if you wind it up in
the gears (autostick), it's got lots of go up to about 2800 rpm & then the
rate of acceleration drops. It will still accelerate very slowly & unevenly
& it doesn't matter what gear or if you are going uphill or not.
I figured if it were a bad fuel filter (it's got about 60,000 mi) then it
would show up more in the lower gears or going uphill, but not so.
So now I wonder if there is an electronic high rev governor that has
malfunctioned but doesn't show a code?
Any  ideas folks, this has me stumped & going to a dealer from where I live
is a whole day's excursion.
By the way everything else checks OK, plugs still look OK, starts easily &
runs fine in D as long as you don't take it over say 2500 rpm.

BCinBC