Bad gas milage

[Leon]

Odd fuel consumption issue that I had for a while. In town, I get
approx 10MPG, not driving
hard, not spooling up the turbo too often, engine warm up or cold. On
the highway, I get approx 25+MPG going around 75mph. Usually run 91
octane from shell or chevron. Car has
approx 140k miles, all stock (doesn't have a CAT), doesn't burn oil.
Stuttering in low rpm range (1000-2400rpm) till turbo spools up,
sounds like it cutting out,
almost misfiring, but once the turbo spools up, its all good.
I believe the engine is running  way rich, some fuel odor inside the
passenger compartment
every now and then. No visible fuel leaks.
That's what I have done so far:
-recently replaced distributor
-replaced recently fuel filter
-Checked ECU - no codes
-checked spark plugs - blackish
-clean air filter
-cleaned MAF
-cleaned ISV
-new MFTS (3 connector, still intermittent operation. Speedo and fuel
gauge not working either)
-replaced temp sensor on back of head
-fuel pressure regulator - gets a good vacuum/pressure

checked air temp sensor - slightly off bentley specs
oxygen sensor - unknown, still looking for a cheaper alternative

Not quite sure what to check next. Thinking about fuel pressure, but
what after that?
As usual, any further help greatly appreciated.