intermittent codes 171+174 lean B1+2
 

Have recurring lean codes, intermittent ck engine lite on. no drivability problems. Cked fuel pressure and was in spec. Replaced the MAF sensr last year, it was setting the same codes and would hesitate and misfire. I can watch the grams/sec reading on my Snap on Modis, but the signal seams erratic. I compared to my 96 e320 and the reading also seams erratic.
Wondering if I need to hook lab scope to signal but dont know what i sould be looking at, or if Im missing something. Thanks

Fuel pressure, vacuum leaks & MAF are the most common problems for those codes.