Fickle 87 325es,, sometimes its fine, sometimes its horrible

[jtuner]

So I have this 325es that i've been working on for over 6 months now.. I finally fixed the dirty gas problem by dropping the tank and cleaning the damn thing out..
When it was all back together, the car fired up fine and ran great!! Well all of the sudden, it started idling rough.. doin a glug glug glug, puffin out black smoke, and idling well under 1k... When you touch the gas the car kills out,,, eventually it'll work its way out of the rough hole and run perfect again...
I'm having lots of problems finding out where to start,, It it was a hibitual problem, I could use a process of elimination, but it only happens every once in awhile.. i'd say 1 and 3 times
If anyone could help with this, i'd really appreciate it... I have 2 fuel filters on the car, and i've changed plugs, wires, but haven't looked in the cap yet... ICV? AFM? god who knows...
PLEASE HELP!!

[AdamF 88iS]

Firstly, put a stock fuel filter setup in there. God knows how low your fuel pressure must be with it trying to pump through 2 filters.

Second, the symptoms sound like an AFM problem. I'd try to find another one to swap in.

[jtuner]

Excellent I'll do both things, but would low pressure and a bad AFM cause it to puff out black smoke when it rough idles?

[AdamF 88iS]

Excellent I'll do both things, but would low pressure and a bad AFM cause it to puff out black smoke when it rough idles?

The AFM can cause that.

Next after AFM is to check if your cold start valve has a leak.

[jtuner]

I changed out the AFM and haven't had the problem since... i think a mechanic i took it to opened the black box where the plug is, and messed it up or sumthin..
But thanks man,, i'm forever indebted to you 8)