I have a stock 03 Z71 with a 5.3 and 108,000 mi and it seems way down on power. I have changed the fuel filter, air filter, and had the cats checked so those things should all be good. It feels good from a stop but any acceleration while moving and it's a pig. from about 15+ in second gear, it's just rediculously slow. Even in other gears when trying to pass a car or just plain accelerate. Of course with 1st being such a low gear, it could feel like it's pulling good even though it's not. I had 2 guys drive it without saying anything about the power and the first thing, both of them said was, "This thing is down on power." Any ideas what could be causing this or what to check? I don't have any check engine lights, btw. Thanks.

Jeff

 

have you noticed any change in mpg....

 

Nope, just checked it at 17.5.

 

I just drove my sister's truck with a 4.8 and her's has way more throttle response and acceleration than my 5.3.

 

have you tryed running a can of seafoam thro the brake booster? See if that free's it up any. check the throttle body? I dunno just idea's. Maybe have someone with tuning software hook up and see if hte computer is running real rich?

 

Mine Was Extremely Sluggish Right Before The Fuel Pump Went Out. Put A New Pump In And Still Ran Bad, So I Checked The Fuel Pressure And It Was In The Low 40* Area @ Idle & 52* At Wot. Replaced The Regulator And It Now Runs Like A Champ.

 

have the injectors cleaned.

 

i was thinkin about getting my fuel system cleaned...can you get that done anywhere? the truck gets pretty awful mileage at about 11.5-12 and now with the converter i think its 10 or a little less with mostly city mixed aggressive and easy....

 

I Had The Injector Service Before Replacing The Fpr, And It Didnt Make A Difference, But It Is A Good Idea To Do It, Just So You Have All Your Bases Covered.

 

I replaced the throttle body (TPS was bad) and replaced the fuel filter. I was getting 54 psi fuel pressure at idle. Anyone know if 4wds just run a lot more sluggish than 2wd? My mom has a 5.3 suburban and my sister had a 4.8 scsb and both of them have a lot more pull than my 5.3 Z71.