e34. idle issue unsolved

Hello,
Its so great getting help when we get stuck with our toys.
well, I have a 1992 bmw 535i.
it had few idle issues but I did everything possible to get it solved.
90% solved now.
what I did....
-valve adjustment as it needed it anyway.
-vacuum leaks to the best i could do.
-icv and maf clean up.
-dipstick rubber washers.
-oil sensor on pen as the oil level kept flickering...now solved.
-oil sensor.
-rubber booths and lines.
-gas cap.
-spark plugs and wires.
-ignition coil as I have seen e34s drive rough.

-the problem is that it will not die or stall,no error codes but in idle its rough and for some reason the dash digital lights flicker a little.
-Just of recent in the last two days with the cold weather in Toronto, the battery light and ABS light come on but go off after 10 seconds.

I bought another e34 from a family friend for cheap but fill bad to start removing and experimenting with parts as this car runs well and drives great...so I will sell it soon.
I think someone else should enjoy it instead of using it for body parts.
so I ask if any one can try and help with this issue I have on my automatic 535i.

Low battery can cause those issues as well. Hook up a volt meter to batt + and see where it's at when running. Anything less than 13 volt is too low.

I did a smoke test today with a home made machine and pushed it thru the vacuum booster brake hose.
found some leak in front near the radiator hoses but it hard to see around there. a little near my ICV plugwhich was weird
as its a electric connector( the one that is just a pin connection)
Going to buy a tester and do what you told me on the battery.
Just getting into the DIY fix part of BMWs and its kind of fun.
Ill keep you posted.
thank you

Testing on the B+ as mentioned by 632 Regal is of course best, but for a quick test you can unlock the OBC and set it to test #9 where you see actual volts. It will fluctuate and that is normal. But if it is always too low, then it might be a problem with the alternator or voltage regulator. On the OBC I see usually about 0.5V less compared to direct test with a voltmeter on the B+ post in engine bay.
How to unlock the OBC: http://bmwe32.masscom.net/johan/obc_...c_secrets.html

Sounds like you have some bad engine/chassis grounds.