Lacking power, check engine light on sometimes....

[bmw318ti95]

Hey everyone,

So im trying to figure out whats going on with my car without spending a bunch of money for someone else to diagnose the problem. My car seems to be lacking alot of power when i get on the gas. Also, when i try and push it hard, as in full throttle to about 5200 rpm, the check engine light comes on after every shift. Driving normally the check engine light does not come on. Also, sometimes upon startup the check engine light comes on, but goes away if i rev it to about 3500 rpm. Finally, my car seems to be idling somewhat rough and at low rpms. Any insight would be greatly appreciated. Thanks in advance.