I believe the EGR tub on the upper intake of a 3400 is like the 3100. YOu have one tube that is a flex tube fed off the exhaust to the EGR, don't worry about that (there should be no need to clean that). But, the port that travels through the upper intake, that's what needs cleaned.

My experience with the 3100 is best to use a stiff somewhat flexible wire (I use a piece of old speedometer cable). Spray in carb clean and fish the wire through until it moves freely through the length of the tube (takes some wiggling to get it through the bend of that tube).

If the blockage is really bad, you may want to take the throttle body off and clean it from behind the throttle body (might as well clean the T-body also if you take it off).

This is again, from my 3100 experiences (which that is that engine is the earlier version of the 3400).

 

Thanks for the suggestion, definitely makes the job a lot easier than having to fight with that tube. In other news...
The Monte Carlo is back!!! Picked it up from the dealership this afternoon, it's a completely different car now. It hasn't run this good for years. It was most definitely the catalytic converter. No hesitation, no lag, no fighting to keep it running 70+mph on the interstate. Unbelievable. GM took care of everything, which was close to $600 (not as bad as I thought actually). 0-60 and 60-90 are just flat out awesome now compared to what it was. We'll have no problems passing on the interstate or keeping up with traffic. It's amazing the difference now. The mileage should go up as well given the significant performance increase now.
I have a few other things I'm going to do now such as clean the egr valve and replace the t-stat and oil pressure switch. I'm also going to stick on a new fuel filter and change the trans fluid and filter. After that, hopefully there won't be anything major happen for a while. Were the 3400 engines ever bad about the timing chain or anything else internal?


BTW, I'm sure everyone has seen a bone stock MC a million times, but here's a million and one (or two)...
Funny bit of history to it... My parents bought it new in January of 2002, in March a hailstorm hit and cause $3700 worth of damage to it. They had to replace the hood and trunk lid and pull a few small dings out of the roof. My Mother was not happy but the insurance covered it all. We bought it off them in 2009 and here is how it sits now...

 

Very nice looking! Especially since it's 8 years old with almost 100K on it.

Glad to hear your issues worked out well. I also recently replaced my Cat. Amazing how much power was being robbed.

 

Nice ride man! Looking at those pics it looks clean. That's awesome to hear your problems were resolved by having the cat serviced and even better, you lucked out that GM picked up the tab for this one!

 

I too had the issue with the Cat and what a difference after that was replaced. So yeah, I know exactly what your talking about Boogie....the whine/whistle you hear when your at a light or stop sign that magically disappears when you hit the accelerator. I have tried to explain that to so many people and they ALL think I'm crazy! Only those that ride in the car with me constantly know what I'm talking about. Soooo, if you figure out what that is, please shoot me a message. I'd love to put a stop that annoying sound once and for all!

sparkyallen1@aol.com

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