P035# issues got me down

Hello all, long time lurker, first time poster here.
Last week I decided to replace my spark plugs since I've never done them and the truck is now at 125,000 miles. I also figured while I was in there I would replace the valve cover gasket since it had a slow seep towards the rear. I read another thread about the preferred plugs to use and went with the

$57 denso sk20hr11 ---- IRIDIUM PLATINUM power pack spark plugs -- # 3421 ----- 6 PCS NEW

denso sk20hr11 iridium long life and purchased them from autozone. During the install I noticed that one of the tips of the plugs was slightly off to one side. I'm not sure if it was welded on incorrectly or bent somewhere in the process of getting from the factory to my hands, but it was noticeably off. I decided to give it a try anyways and sure enough started the truck and it was missing. Proceeded to pull the coil wires one at a time and sure enough it was the bent one, obviously. Anyway, went back to the store to exchange it for another one. While I was doing the exchange I opened the box to look at the replacement, and it also looked slightly off so I opened the other 3 boxes and noticed the were all slightly funky in one way or another. The one that looked the the most straight had a bit of welding slag on the arm portion. I figure that its probably not a problem so I go with that one. So I go home get the thing back together, fire it up, idles rough for a few minutes drive it around the block, roughness goes away and im happy.
Next day take it up to the Olympics and im heading up a pretty rough hill and a cel comes on. No noticeable issues so I spend the night and drive home the next day. Truck seems to be running alright, im not too worried since I've been having an intermittent p0420 for a while that I've tried remedying with a spacer. Drove the truck for another week and now I'm starting to get a rough idle feeling, not terrible but noticeable and also intermittent. I drive to the autoparts store and put a scanner on it and im throwing all p0351-p0354. I decided to check all connections and make sure all coils were seated correctly and everything looks good. So I disconnect the battery to reset the codes. Took it for a drive and no cell, but still intermittently idles rough.
So here's my questions
1. how long would the new cell take to return after resetting the ecu?
2. Would improperly gapped plugs throw a p035# code?
3. Any wise suggestions, or should I continue to drive it to see if the cel returns?

 

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