325 "Stumbling"

I have been having ongoing issues with my 95 325. I will try to be as brief as possible with the description and the work that has been performed so far, to no avail.
The problem is that you will be driving along and all of a sudden the car will start to flutter and try to die. If I give it full throttle it will clear for a moment and than the rev's will fall back off again. If while I am rolling, I will put it in neutral, turn it off and immediately restart and all is fine for a while. So far I have:
Cleaned ICV valve
replaced all vacuum hoses/o rings
rebuilt VANOS system
replaced spark plugs
checked fuel pressure-49-51 lbs consistently
fuel filter changed
Replaced rubber intake bellows between MAF/throttle body
replaced MAF
pulled all codes from DME. Only getting LAMBDA sensor 1 which basically is a fuel/air mixture problem.
Replaced O2 sensor
replaced DME
replaced injectors

I can not get the car to do this consistently. It is dangerous because I will be at an intersection and it will all of a sudden kick in and no power. When it is running well, it is absolutely fine. Today it started to do the stumbling thing. I floored the accelerator and the revs would jump right to 4-5K RPM. If I tried to hold it there it would just fall back to around 1K. I don't have any TPS codes showing up, but am wondering if this might be an issue. This problem is driving me nuts and we have a smoke test set up for the intake on Friday. I just don't know whether to go after ignition or fuel supply. Any thoughts would be helpful. Thank you

Originally Posted by capecodbmw

I have been having ongoing issues with my 95 325. I will try to be as brief as possible with the description and the work that has been performed so far, to no avail.
The problem is that you will be driving along and all of a sudden the car will start to flutter and try to die. If I give it full throttle it will clear for a moment and than the rev's will fall back off again. If while I am rolling, I will put it in neutral, turn it off and immediately restart and all is fine for a while. So far I have:
Cleaned ICV valve
replaced all vacuum hoses/o rings
rebuilt VANOS system
replaced spark plugs
checked fuel pressure-49-51 lbs consistently
fuel filter changed
Replaced rubber intake bellows between MAF/throttle body
replaced MAF
pulled all codes from DME. Only getting LAMBDA sensor 1 which basically is a fuel/air mixture problem.
Replaced O2 sensor
replaced DME
replaced injectors

I can not get the car to do this consistently. It is dangerous because I will be at an intersection and it will all of a sudden kick in and no power. When it is running well, it is absolutely fine. Today it started to do the stumbling thing. I floored the accelerator and the revs would jump right to 4-5K RPM. If I tried to hold it there it would just fall back to around 1K. I don't have any TPS codes showing up, but am wondering if this might be an issue. This problem is driving me nuts and we have a smoke test set up for the intake on Friday. I just don't know whether to go after ignition or fuel supply. Any thoughts would be helpful. Thank you

Well my first 2 thoughts was MAF and DME which you replaced both...sounds like fuel problem to me though. how long has it been doing this?

B1, thanks for the input. It has been doing it since last summer. I initially unplugged the MAF and it did not run correctly but at least it didn't die on me any more. I replaced the MAF at that point since I figured that was the problem. But no luck, same problems. I let the car sit for a few months and now I am back to trying to diagnose it and fix it once and for all.
Thanks

I know this is a more than a year later, but I have a '96 320i doing the same thing. Hoping you found a solution before I try the same things you did (thank god I saw your post before all that work).

Have you tried replacing the DME and or Fuel pump relays. I've seem similar behavior on other ( non-BMW ) cars, and it was a the fuel pump relay. It worked most of the time, but then it didn't intermittently, and the car would loose power. Turning it off could be reseting the relays. I'd also check all the wiring for some frayed wires or a loose ground.