Okay so I have a 2007 e90 bmw 328i, it’s 3.0l i6. I believe it’s an n52 engine. I’m just gonna start where my problems began because it’s kind of a lot.

I wanted to add a cold air intake so I bought some couplers and pipe fittings as well as a filter to save money and installed it and ended up damaging my MAF sensor. I drove with that intake for 3 or 4 days before I went back to stock airbox and on the 4th day it started stalling on me and overheating and CEL came on, a MAF code.

so I cleaned the MAF sensor and it didn’t work so I ended up replacing it with a new MAF sensor. I had trouble finding the right one but this has seemed to fix it a bit. I started heading to oreilly’s to get some seafoam and when I got there I heard a loud hissing noise coming from the engine bay, and it stalled multiple times on the way home So I ordered a new valve cover and replaced it. It fixed the hissing form the vacuum leak, I believe the cover was cracked.

I let it idle for 20 minutes and it seemed fine but then I drove it and it stalled on me again. But when I restarted the car the CEL went away and it started driving better. After driving it a bit more CEL came on again, I haven’t ran codes yet, But I’m still experiencing rough idle at start, rpms dropping on deceleration and then stalling, overheating, long crank, poor gas mileage.