Hi, I have a 740 that when in park, idles just fine, but when is revved above 1500 rpm, it loses power until the rpm needle gets below 1500 rpm. Then the engine kicks in again, untill it gets above 1500 rpm. If I have the gas pedal pressed down, it keeps going through this cycle, where it revs and momentarily cuts out and then revs again. --This is also the case when I'm taking it down the road, as long as I keep the rpm at 1500, the car will continue to pick up speed untill it reaches about 26mph to 27mph, but in order to go faster than that I have to increase the rpms, and then it momentarily cuts out. When it is parked and when it is on the road, up to 1500 rpm, it runs and sounds perfect.
I think this is an electronic problem. The code that I got from the black box under the hood right up next to the stering wheel, was 2-3-1, which I belive means "mixture too rich". I cleaned the air mass flow sensor right next to the air filter, and even replaced whith a spare I had. I changed the knock sensor, It has a new radio supression relay, and a new fuel injector relay, also a new fuel pressure regulator and new fuel pumps.
----If any one has any sugestions please help, as this is my primary transportation. Thanks, airik777

check the ignition system. any load increase from the motor on a weak coil, plugs, etc., can cause this. weak ignition can look like too much fuel. i would also check the fuel pressure. just in case something new has gone wrong. pressure regs can fail to high pressure just like they can fail with a leaky diaphram. it does sound like weak ignition instead of too much fuel. good luck, chuck.