For sometime now, I'd occasionally get a P0171 (Right Bank Lean) and momentary Restricted Performance. I thought I'd checked everything. I always inspect my air intake duct and bellows whenever it's off the car.

This weekend, while putting in some new spark plugs, I believe I found my Gremlin. The main intake duct itself was fine, .... but there was a 1/2" x 1/16" gap in the seam of one of my "Sound Tubes" (or what ever they're called). I had never thought to inspect all those tubes. I have no idea how long that has been there.

I mixed up some quick-setting epoxy; put a fair amount into & onto the gap; and slowly rotated the duct over and over so the epoxy stayed in the proper locale until it set. (My neighbors have long since stopped commenting on all the strange activities they witness in front of my garage - lol).

Anyway, if you're getting P0171/P0172 codes and everything else seems OK, give those sound tubes a closer look-see.

 

Could that be the full load breather from the front of the cam cover to the inlet duct?

 

Nope. Just the duct running from the MAF to the throttle body. I must have six or so of those sound tubes sticking out from the thing. Very "Medusa-like". ;-)