Morning, Friends:

1986 240, B230F/M46, 335,000 miles.

This started last Friday. The car has no power above 2500 rpm. It's like it hits a wall. Now, if you are going downhill, the engine will run above 2500 if the car picks up enough speed, but it will not accelerate over 2500 on its own.

My first thought was the air mass meter. I swapped in three "known good" AMMs to no effect. I've also replaced the o2 sensor.

Cap, rotor, plugs, wires are less than 6 months old. The entire exhaust, from the catalytic converter to the tail pipe, was replaced in 2014.

Strangely, fuel economy remains the same as always.

Stumped on this one, and it's a frustrating one! There is a grade on my commute that I can normally take at 70 mph in 4+OD. Now I'm taking it in 3rd at 40 mph with my foot to the floor.

Any help much appreciated!!