Car Won't Rev

[glurft]

Hello, I have a 1989 325ix 5 Speed that runs extremely well other than one problem. When the car has been driven for a long time (30+ min), or driving on it hard (reving past 5k multiple times) The car will stop accelerating at around 4500 RPMs. It feels as if I just take my foot off the gas pedal completely even if I keep the pedal on the floor. If I continute to drive on it, the car will slowly die down to not rev past 2.5k.

This happens the worst and most commonly when I have 1/2 a tank of gas or less. (My gas gauge is also not accurate if that means anything). Any input on the situation would be greatly appreciated, thanks.

[wodcutr]

Fuel filter is plugged up with debris so not letting enough fuel through to maintain the fuel pressure. I would bet your fuel pump is also about to die too from working so hard.