Can anyone help,

I have a 96 850 T5 saloon,

When cold or warm if you accelerate normally up through the rev range, when the revs pass through approx 2800 to 3100 revs, there is a very quick but noticeable lull in the engine. It feels like a slight misfire. If you accelerate hard though it doesnt do it. Overall it feels like the car is labouring slightly however it leaps away if you then put your foot down.

It idles dead on every time but one day not so long ago, weather fine, traffic fine, not running hot, it spluttered twice for a split second. it has not done it since and i put it down to a bit of dirt in the fuel.

I have changed the air filter, put semi snyth oil in it changed the oil filter, gearbox oil and cambelt and the plugs in order to start with a clean slate but this is puzzling me as everything else is fine. Apart from the clutch needs doing.

The plugs i put in were the ones recommended on the OzBrick website in an attempt to sort the problem however it is still there.

Any ideas would be great...cheers

P.s. i spoke to a Volvo specialist, he had not come across it before, hope one of you guys has ?

Cheers

Vince