Within about the past month, I have noticed my 240 has been idling rougher than normal. It has never been smooth but I would say now that it is notedly rough usually.
Shortly thereafter, I noticed a dramatic drop in fuel mileage on the highway. I used to get at least 23-24 mpg and sometimes got up around 27-28-29 mpg. However, on the last tank of almost entirely highway driving it has dropped to around 19mpg.

I snooped around, pulling and plugging different vacuum lines trying to find a leak, didn't find any glaring ones, but I plan to try to pull a vacuum and see if it holds it, to ensure no leaks.

However, the drop in fuel mileage has me wondering if it isn't running rich. However, I haven't noticed any black smoke and the plugs didn't look bad when I pulled them.

Still, my latest idea is the FPR. I know that a sympton of failure is that the vacuum line feeding the FPR smells of gasoline. I pulled it and sure enough, it reaks of gas. However, no liquid fuel was present.

So, can the FPR be failing, but only slightly? Enough to make it run a little rich and produce rough idle and poor fuel economy? Or do they usually only catastrophically fail?

Any input is greatly appreciated. Thank you.