1995 945 8-Valve, NA. 248k miles

I suspect that my is running a bit rich - not enough to kick a CEL, but fuel consumption seems rather high (1/4 tank of an 18+ gallon tank burned in 40 miles with half on the highway?) My wife typically drove the car on highways with some mixed city and has experienced some very poor mileage. I generally chalked it up to tired engine, but after driving it myself for a couple weeks, I suspect that there's something out of the ordinary.

For one, the car also has some weird hesitation when being given throttle, but cruises fine on the interstate and generally around town. The engine also sounds just a little bit "odd." and the burnt hydrocarbon smell seems a bit strong when being idled. I don't have any black soot on the tail.

I checked for cracked hoses, bad gaskets and the like, using cleaners, and waterspray but haven't found anything.

O2 sensor is new as of a year ago, FPR was replaced a couple years back... both are Bosch. Single fuel pump is OEM Volvo and only about 30k miles on it. Temp

sensors were all replaced about the same time as the FPR, but I suspect the FPR might be a problem... Slight fuel smell on it when I pull the vacuum hose (which is a 4mm silicone hose), but it is not obvious and possibly not out-of-the-ordinary.

Last time I had a bad FPR, the main fuel pump was buzzing and the car was very obviously running rich - stalling, and sounding strange.

I'm not to that point yet, and I don't want to get there.

Is there an effective way to check fuel pressure w/o buying special tools?

Was considering that IPD air/fuel meter thing - any thoughts on that?