ive searched and searched and searched, i cant figure this one out! i have a 95 318ti and i love this car, but it idles rough, and sometimes dies. i did the stomp test and got 1226 knock sensor #2 so i changed all my spark plugs, changed oil, pre cat o2 sensor, and checked for vacuum leaks, it didnt help. so i cleaned my icv, didnt help. im pretty sure my mixture is lean so i bought a new MAF sensor and im currently waiting on that. but something weird is when i take my oil cap off it doesnt have suction, it has the reverse it blows out not sucks in. can any body help me figure this out?
Rough idle, dies, Failed smog 
Linear Mode
