cj7deerslayer

i have a 2001 5.3 4x4 silverado auto trans.

this problem cam on very suddenly.

the other day it would shudder going up a hill and gave p0171 and p1074 codes / running lean.

i cleaned the mafs and throttle body now it runs even worse

idle is fine but the engine shakes a bit on start up

i disconnected the mafs with no change

truck runs fine on level ground under light acceleration. but going up hill or hard acceleration the engine either chokes down and tries to die or just wont rev up. occationally it will rev up a bit but not enough to get it up a hill at over 25 mph.

after cleaning the mafs and tb the service engine light went off, but still runs very poorly.

there was a fuel pump installed at the dealer where i bought it in march at least according to them. they may have put in a used on for all i know.

any ideas?

old dog

might try a fuel filter ,bad load gas ?

speedy58

i would say since my uncles was doing the same its the CATs. but could be other things too.
but his was doing same thing ran fine till hit the gas unless you hit it real eazy.
we took out the cats and (AKA) put new cleaned out cats in.
and ran great no more probs. at all.
but to truly replace them there pretty exp.

jkgray80

You got system too lean codes but cats fixed it?

jkgray80

Sorry , didnt realize a different person posted last reply. Has the telltale signs of low fuel volume. Dont forget new parts can go bad early. I would suspect pump. What did you clean MAF with?

chevyboy@22

You got system too lean codes but cats fixed it?

mountainmanjoe

Please check post dates before you reply to dead and buried ones.