Volvo 8 Valve Non Turbo
120,000km

Experiencing low gas mileage, about 16mpg.
Seem to have gasoline in the engine(able to smell gas in the engine when removing the engine oil cover).

Thinks that I have checked and replaced:

Spark plugs replaced.(no improvement to fuel mileage)

Oxygen sensor changed a week ago (no improvement to mileage)

Fuel Pressure Regulator:
1. Checked by unplugging the vacuum line while idling. No fuel flowing out.
2. Remove the fuel return line and fuel was pouring out from the FPR.
3. Unplugged the FPR while idling but did not notice any surge in RPM.
I don't know whether this is any indication of a faulty FPR but the other two procedures suggest that FPR should be okay

Injectors removed to check for leak. Crank engine and stop and then wipe injectors dry to see if more fuel comes out. None. I suppose this means injectors are okay. Spary pattern not perfect but not too bad (couldn't expect anything more for a 120,000 km run). Also able to hear ticking sound on the injectors (using a hose) when engine is running.

The FAQ suggested these are the possible causes for fuel to be in the engine. All tested okay. What else could be wrong that is causing the mileage to be so low. It used to 22mpg before.

Bricksters, your expertise is needed. Please advise.

Thank you in advance.

Laozong