I just had a couple codes come up on my '96 Blazer. P0131 and P0151, which is basically O2 bank 1 and 2 lean. First thing I do is search the net because someone has always had the problem before me. I read everything from a bad fuel pump, to a plugged cat. to fuel reg/injector assy, even several people thinking that two O2 sensors would fail within seconds of each other. Guys have even been convinced to get their transmission rebuild because it was slipping.

Symptoms were:
-smooth idle
-started like new
-revved fine in neutral
-fuel pressure and leakdown well within spec
-engine would surge at low RPM(1500) with trans in OD lockup
-engine would not rev beyond 3000 rpm under load without misfiring
-at WOT, accelerating on level ground it would not rev past 4000rpm and severe surging
-new Delphi fuel pump had a noticeable whine


At any rate, mine was simply the fuel filter. Makes perfect sense, and it was the first part i tried because it was the cheapest.

I was going to add this to a thread that had a lot of mis-information, but they were all closed. Hope this saves someone a bunch of money...

 

good post Diaita