help, 540i/a still running rough

[tim s]

my 540i/a is still running rough around 1000-1300 r.p.m.s. it is driving me crazy, it seams to run a little lean, when the temp outside hit 70 the car ran smoother, in the past 3 months replaced plugs, boots, o2 sensors, icv plate, did injector cleaning service, compression tests o.k., but still runs rough. dealer claims it's fine, but i noticed a lack in power, even at the upper 5000rpm power band that i really enjoyed. i am running out of idea's, we also tried to find vaccuum leaks. found no leaks. i am looking for more suggestions. could it be a temp sensor?
thanks
a very frustrated tim s.
1995 540i/a
1987 325e

[new540iwoner]

you may want to replace the Oxygen Sensor Heater Relay. I replaced mine
and the car runs fine.

[winfred]

i've had v8s come in throwing intermitant o2 sensor codes and running bad at certain times, plugged cat/cats is one cause and another being intake manifold gaskets, the intake gaskets can be a bitch to find because they don't always leak, some times they seal up when the motor warms up, we just did battle with 3 e38's in a row that had intake leaks and or plugged cats in the last month. they use gaskets of the same materal as a m50 but i guess the amount of oil that the v8 ingests through that crappy pcv system kills them, i don't even bother changing the gaskets on m50/52 when i need to pull the intake, they seal up great, but they get rock hard and crack on the v8, if you change them don't forget to do the throttle body gasket too

[tim s]

compared to the valve cover gaskets.
thanks
tim s.

[winfred]

a little, you need to dissconnect and lay the wiring harness off to the side before you can pull the intake