I'll check for the secondaries, it could be very possible that they stay open all the time...
Originally posted by SpliceVW:
The rotton egg smell though.. that's supposed to be your cats. You say you've checked the cat.. what about the pre-cats?
The smell is now gone, as strange as it looks, it was the intake manifold that have been clogged with carbon deposits. They cleaned it and the smell and the CEL are now thing of the past 
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The car is driven mostly in town, and that's what probably caused that much deposits in the engine.
I've drive the car yesterday and I noticed that when the engine is started, it rev up to 1500-2000RPM for a minute before get back to 750RPM. I don't use that car very much, but some years before, it would not rev that much.
Also, it run a little rough at idle, and nearly stall when put in reverse, then rev to 1500RPM after when I put it back to neutral, like the engine need to adjust the idle a lot to keep it running in reverse.
BTW, thanks a lot for your help, I'm a newbie in cars mechanic but I like to learn a lot . 
