Hello, my father purchased a used 2007 ES350 about 6 years ago. It had about 111,000km on it at the time of purchase. He rarely ever drove it. About 3 years into ownership, an engine light came on. At that time it would shudder a bit, sometimes while idling, sometimes while driving. It was checked out at a local Toyota dealer and a code came up for an ignition coil on #1 cylinder. They gave him a quote for over $800. Just curious, could this problem resolve itself if driven more frequently? He's only been driving it about 1000km/year and it sits for 1-2 weeks between use. Any advice is highly appreciated, thank you.

 

No. Coils on these engines are known to go bad. Our 07 has had 4 coils replaced, the first one at about 70K. Yec Flamma is a good aftermarket coil. #1 cylinder is far left as you face the engine and the coil can be replaced without having to remove the intake. If the spark plugs are near 100K miles, minus well replace them all, and maybe all those coils along the firewall as well, keeping the oem coils in cylinders 3 & 5 as backup. IGC112F is the Yec part #; about $35.

 

I would rather get 6 from Amazon and new spark plugs for about 120 dollars and replace yourself or go to a mechanic.

 

No, coils never fix themselves. The cost is high because coil #1 is on the rear bank, meaning that, to do it properly, the intake needs to come off (and have a replacement gasket etc.), that's why the dealer price is so high.
However, it is possible to do it without removing the intake, you just need to remove the wiper cowl, find a local mechanic who's done this before for the 2GR-FE and he should know the tricks.
I would recommend OEM (Denso) for the coils, the new coils Denso make are a bit better and you only need to replace the ones that break.

If you ever find yourself having 2-3 new coils and coming up to do spark plugs, better to remove the intake and put all the new coils on the rear bank and the old ones on the front bank, to save yourself time and effort down the road.

 

Find a good indpendent Toyota specialist shop as they will be much cheaper than a dealer for this work. Try Google and Yelp for reviews, or the regional forums on this site.
$800 is robbery to replace the coils, let alone just one coil. At that price all 6 plugs and coils should be replaced but it is still too expensive.

 

Here's a video of it done with taking the intake off by a Toyota tech. Here's a video of it done without taking the intake off (more trickier).
Though it is possible to do without taking the plenum (have done it). But it was a huge pain in the ***. That bracket along the back no matter what leverage me or eventually my friend (who had to help me since I was stuck) gave, it wouldn't budge. Had to buy swivel sockets and some other stuff and then use my impact gun since it still wouldn't budge. Holy hell. What made it worse was I could only do this at my friends, so I had to reassemble since we couldn't finish and disassemble again a few weeks later when the tools I ordered came in. I gladly would pay if I knew the pain in the *** it was gonna be, but I guess since I have the tools now, I'll be okay if I had to do again.