First time BWM owner needs your help. Took in some water during hurricane weather last year, cold air intake. Engine rebuilt, and has never run the same. Instead of a new engine, dealer said only 2 cylinders needed to be rebuilt. Since then have had the air mass handler replaced, new battery, coil packs, fuel filter, and still rough when started. After you rev 3-4 times it levels out. After each "fix" would run fine for a few days, and then the same problem. Any suggestions would be appreciated.