1994 318i e36 idles rough.

Hi, I have a 1994 318i e36 BMW with a rough idle problem and flatspots when reved with backfiring through the intake system. Also the mixture is rich (black smoke) and there is no error check light illuminated on the dash. I replaced all the engine vaccum hoses, spark plugs and cleaned the icv but the problem is still present. I am open to any ideas.

YOU NEED TO SEARCH before posting the same question that has been asked many times.

Clean, Clean, Clean the MAF.. remove screens on MAF, use spray FIRST, (and LIGHTLY with q-tip if necessary) clean the element.
Clean Throttle body
Clean Throttle position sensor
Check for vacuum leaks
Check the hoses that are plumbed into the boot on intake

Disconnect, clean, lube, and reconnect all associated electrical connections.

Ok thanks for the info will implement and see if there is any improvement. I'm new to the site but i will in the future check all available threads of similar content to aid in my troubleshooting.

In addition your Idle Control Valve might need a good cleaning. Very important to check the two hoses for cracks. Just did mine Sunday morning. It's going to take a hour at most. There's a pretty good write up on bimmerforums google it. The rear boot on the intake manifold is going to be tough suggest hitting it with good ole WD-40 and using the closed end of a combination wrench also when putting it back on pre screw the bolt back before placing it the bracket.