ok so i have a 2001 monte carlo ls and it stalls after driving it for so often and when i try to press the gas on bigger hills. I am getting code p1404 for the egr but is that really the issue? pleeeeeeez sum one help as ive been to mechanics and they seemed knoledgeless

 

The 3400 is based on the 3100 and I saw a BUNCH of 3100's where the tunnel connecting where the EGR sits that leads right behind the throttle body (it's cast aluminum that is part of the upper intake) is gunked up with crud deposits. The fix is EASY. Remove the EGR, get something some what flexible and longer then that connecting tunnel (I use an old piece of speedometer cable, works great). Spray carb cleaner down that tunnel and try running that speedometer cable through that tunnel. Once you get to the point where you KNOW it has ran all the way through, spray more cleaner in and run that speedometer cable in and out a couple of times.

That is my first "guess" without looking up that code.

 

Should i just replace the egr valve? I want to get to the root of y im stalling

 

If your problem is what I described replacing the EGR will NOT fix it as it's NOT the EGR. It's the tube that comes off the upper intake that's plugged (this tube is cast aluminum and is part of the upper intake, there is NOTHING to replace).

I tried searching my 3100/3400 pic collection and I don't have any of a engine clear enough to show the passage. But if you unbolt the EGR, you will see a tube that pulls up to the EGR when it's bolted in (this is NOT that tube), but looking where the EGR mount, you will see a passage way leading into the upper intake. This is what needs cleaned.

The process I described takes about 10-15 minutes to do for a first timer (once you get the right tools for the job).

 

Oh yea i forgot im getting p0420 for the cat and also wen it stalls i have to wait acouple hours b4 i cant start it and even then she' ll only run for a very short period after that

 

If your cat is clogged, it's going to stall it out. The exhaust can't get through and out fast enough so it backs up into the engine and chokes it. Replace your cat.

 

I'm inclined to agree with Mogwog. BTW - if that is the factory CAT, never been changed, the '00-'01 W-Bodies (Monte is part of that) had an extended warranty from GM regarding bad cats from their supplier. But I think you are past that extended warranty.
A plugged cat is a serious problem, if left unresolved, it will eventually cause more serious problems.

 

So u guys are saying that my cat is clogging up as i drive it for so often then stalls out and declogs itself after a few hours?

 

It's not clogging/declogging. The element inside the factory '00-'01 cats are none to fail (GM got a bad batch of cats those years). When things heat, they expand, so if the passages in the cat have reformed, it's possible they are closing up.

Here's something you can do.... After you drive the car a little while (less then 15 minutes or so), leave it running and in park, get out and look under the car. If the cat is cherry red (possibly glowing), you have your answer, it's a clogged cat.

 

the original cat was replaced by the second owner, and it take alot more than 15 min or so b4 it stall ..ive driven an hour and a half on the highway with no problem , ive never stalled on the highway it happens going up steep hills or driving it for so long around a city