The old o-ring getting stuck in the rail happened to me on multiple injectors. The injector was stubborn to pull out on those where it happened, as the injector had to be pulled "out" of the o-ring.

It wasn't an issue at all though other than the injector being stubborn to remove. You just use a pick tool to take the o-ring out of the rail. The o-rings were otherwise intact and it's the only engine I've ever seen this happen on.

Replacing the injectors or refreshing them is overall an extremely simple job. I wouldn't overthink it, it will be extremely obvious how everything goes together once you get to it. The hardest part is getting the rail off, as you have to move the electrical harness boxes out of the way and that can be quite annoying. I did mine with the engine out, so it wasn't that big of a deal for me - but I removed all the rear connections and draped the electrical stuff forward over the engine. With the engine in place you'd probably want to use bungee cords or something to pull them away from the engine...


Personally though, I doubt the issue is a leaking injector - a leaking injector won't leak only when cold and in fact you'd smell it more and more the more you drive it. There is a vent line that may have deteriorated, which will only be open to the tank (more correctly, to the charcoal canister) during certain times - so this may be possible, but I am not sure the exact times these engines do that DMTL test. It could also just be some sort of vacuum leak, as the engine runs richer during startup, so you may be smelling excess unburnt fuel if there is any sort of vacuum leak present.

IMO it certainly merits further diagnosis.