Trans and tq replaced 9,000 miles ago under warranty.

Full throttle accel is fine, so I'm suspecting the fuel pump is putting out correct volume and pressure or it would starve at high rpms under load. It's only the part throttle responsiveness that goes away. At maybe 3/4 throttle it's all back to normal power.

Plugs changed maybe 2500 miles ago, at 87,500 miles. They were original and looked fine, correct color and uniform from cylinder to cylinder. Fuel filter done at the same time.

I can be driving along with everything working fine for several hundred miles then like a switch was thrown it feels like I've lost 20 or 30 lb-ft of torque in that 2500-3000 rpm range. No gradual degradation of power.

__________________
'04 E53, 4.4 Sport
'97 E39 528i
'86 911 Carrera, track car
'96 BMW R1100R