2005 Impala gas smell - no visible leak

There is an odor when it idles both in and out of the car but only after some driving - if I sit there a while the smell goes away. It is most noticeable when I get off the highway on my way to work and sit at a stop light. If i have to sit and wait for someone, the smell dissipates. I cannot find a leak. There is a performance issue but I’m not sure if it’s related. At highway speeds it is having trouble accelerating - if I’m at 55 and want to go to 65, it’ll go but it feels like there’s resistance, almost a pulling, it causes the car to rock back and forth a bit - again it only happens at higher speeds.
It has 140000 and is in good shape (except for things mentioned). The last repair was a water pump replacement about 4 months ago.

Well, all I can say is that you have to get it to someone who can find the leak. What have you done to try to find it?

It’s quite possible that it is involved in your highway speed issues. A leak will be messing up the fuel pressure which has to remain within a fairly specific window.

Knowing how poorly GM fuel injectors seem to age, I’d go there. I’d bet on it.
Whenever I’m at a stoplight and smell fuel, I look around and there’s an aging GM.

The gas smell might be from a fuel injector O-ring leak.

Start the engine and while someone looks at the fuel injectors rev the engine. If there’s a leaking O-ring they’ll see it.