New to e36

Sounds like a MAF or a vacuum leak, google the code to see what it says. then after you do that, report back with the info and we may be able to advise you on how to diagnose the problem. But we need need to know the essentials, Year Make Model, mileage, mods? recent maintenance? We've got no clue if you're in the wrong forum or if you have a 4 or 6 cyl E36 or if you drive a Ferrari.

the secondary air pump is a common failure, but you should first check the fuse for it and then try to jump the motor at the connector to see if it even turns on. there's also a check valve that stems off of the exhaust header that is prone to failure as well. These give the DME information and a signal at start up and at idle to lean out the fuel mixture and pre-heat the catalytic converter. Without this part, the DME sees no signal and resorts to a default mode when cold idling which can result in an erratic or jumpy idle depending on what the up and downstream O2 sensors are giving the DME for a reading.