Any GM mechanics?

[F16CrewChief]

got a 97 silverado with 5.7. seems to have a stumble/stall at anwhere from half throttle to wide open. wont acclerate just acts like a rev limiter. soon as i back the throttle to less than half i get power back and can accelerate. tried everything except a distributer....

[BLKrinnyrdr]

 I just had to cut my future Brother in laws cats off and replace them with straight pipe, dealer ran diagnostic and told him that was the problem, or part of it. He has an .01 or .02. He had the fuel pump replaced under warranty too. Cost you 80 bucks, but most dealers will run full diagnostic and give you a print out of all the findings. Autozone will run one, but it is hit or miss on accuracy!

[Mike_Wren]

Not a GM mechanic per say, but have turned a wrench or 2..  Anyways, you have definitely described your catalytic converter going out or "clogging" on you.  They have what amounts to a honey comb inside of them.  They tend to break down over time and prevents exhaust from escaping putting a large amount of back pressure on the engine.  It will eventually go completely out and you wont be able to go at all.  You have a couple of options.

1.  Take it off and knock out the cuts and put it back in.  I don't recommend this as it will destroy your fuel mileage significantly.
2. Do like BLK said above and put straight pipe in. Really same as #1, but again I don't recommend for the same reason.
3. Take it to an exhaust shop and have a new one put in.  Really not that bad on cost and better for you and the truck in the long run.

[Stuntmanmike]

I have a profesional scan tool if you would like to see what codes are shown.

[jr88]

ck voltage at tps

[BLKrinnyrdr]

 Brother in law actually gained a little mileage out of it, but probably because he did tune up, cam sensor and fuel pump all in the same week. But Imo, which could be squat, sounds like the cats. Open her up let her breath man. FYI too, most exhaust shops will not touch your system if you have no catalytic convertors on it. So if you cut em off, and try to have straight pipe welded in, they will not touch em! Cost to replace both of his was around $500. I wish I could find somebody to cut mine off and run straight pipe all the way to the flow master, but I just like the sound, lol!

[Roudy]

EGR Valve

[Mike_Wren]

His is older so it wont be no where near that cost and he should only have one.  As for gaining mileage, I am surprised that he did even with the tune up, but that is awesome.  As for exhaust shops not touching it if there is no cat, that is correct.  It is actually illegal to run a vehichle with out it, that is why they wont touch em.

[Stuntmanmike]

If you want to cut off the Cat's and put on straight pipe, I can weld it back together for you.

[450foremanstaydeep]

As long as it's not a chain shop some will just tell it's a race truck has worked for me in  the past. but this is crestview

[Buckeye]

Only other thing than clogged cat could be mass air flow sensor doing that.

[Roudy]

Top Gun wont work on it, Im actually having the same probs with my malibu now, I thought it was fuel filter, not that. I hooked it up to a comp, n its either the EGR, or cat for my car. Im gonna cut my cat off n put a piece of pipe in there n see if it fixes it. If not then im gonna go spend the 70 bucks n get the new egr valve

[Buckeye]

Some EGR's can be taken apart and cleaned.

[Roudy]

Mines not one of them lol Tried that Monday Night haha

[450foremanstaydeep]

I know from personal experience a clogged cat will melt the egr valve down