EGR Flow Insufficient - Protege5 2003 - P0401

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2003 Protege5
Rough Idle, also getting P0171 (System Too Lean) and P0302 (Cylinder 2 misfire). Car was fine until this happened a week ago, no CEL on, and then everything was lighting up, CEL flashing intermittently.
260000 miles, car burns about 1-1.5 quarts of oil per 3k miles. Other than that, this vehicle is and has been rock solid.
I have replaced the EGR valve, but didn't notice any difference in the idle, and driving was still rough. (I also didn't disconnect the battery to clear the ECM, or let it idle for 15+ minutes like people were recommending).
$200 part, so I'm going to focus on cleaning and reinstalling the original EGR valve if possible.

Question is, I saw some recommendations on cleaning either the throttle body and/or the manifold. I didn't know if the Exhaust Gas path back to the EGR valve was likely to clog up, or if that was a straight shot that usually stayed clean. A video of someone cleaning a Mazda P3 (?) showed a completely clogged tube going from the exhaust manifold to the valve.

Anyone know of any resources showing a walkthrough of removing and/or cleaning an exhaust manifold? Or is that unlikely to happen, and I should focus on the EGR valve and retraining the ECM?
 
You've got alot going on there. 1st we can address the misfire(p0302) change your plugs, coils and wires. Most likely this is the cause for the flashing CEL. 2nd the lean code could be a cracked intake tube. Check the accordian portion of the tube for cracks. The EGR might be new however, the tube going to the exhaust manifold can be plugged. Try pushing something like weedwacker line into it and see if it gets stuck. If so, you can remove and clean out with throttle body cleaner. If it is shot, an easy replacement is gas line for like a dryer. Also, on top of the throttle body is a plate with JIS screws (they look like philips but are slightly different). If you remove that you will see small passage ways down into the throttle body. Liberally spray the TB cleaner into those passages along with the hole just inside the butterfly on the bottom of the TB. Those get gunked up and restrict airflow for idle and the EGR also. Its probably best to remove the EGR before this so you dont ruin a new part. Removing the battery will clear all your codes and give you an idea of what worked and what still needs to be addressed. But your car will run like crap for up to 100 miles. Mine clears up after 20-30 tho
 
Thanks for the response, sleeprp5.

Already checked the intake tube - I've had to replace that a couple times already, so that's been my go-to check if I'm having engine trouble.

I was able to clean out the EGR valve without having to replace it. I was able to push a weedwhacker line at least a foot up into the EGR port, so that seemed good. I Opened up the carburetor valve and sprayed carb cleaner into the port right inside the carburetor a few times just to be sure. Test drove again, and CEL came on again after hitting highway speeds, but only got the cylinder 2 misfire code. (EGR insufficient and System lean codes didn't come back). Replaced the spark plug and swapped the coil packs, and the cylinder misfire code switched sides with the coil pack (cylinder 4 now), so I'm pretty sure I have it figured out. Coil pack had a grey spot that looks like residue from an electrical arc. Coil packs are replacements with a lifetime warranty, so I just have to track down where I bought them from (AutoZone?).

Seems strange to me that I would get two things going wrong like this at once, but I guess that's just my luck.

Anyway, thanks again. I'll try to check in once I get the coil pack replaced to confirm that this is fixed.
 
Sounds like its pretty much figured out. Always nice when its back on the road! Ive read a lot of horror stories about sub par coils. Some guys have good luck with house brand coils while others have nothing but headaches. I have had good luck with Hitachi brand coils. Either from rockauto or sometimes the import direct brand from oriellys. Trick is to look at the brand or country of manufacture. Whatever route you take - congrats on fixing all your issues
 
If still rough idle, make sure the IAC is also cleaned out. Usually goes hand in hand with cleaning the EGR.
 
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