Would appreciate view on the following problem. I've had a search through the site and got a few ideas, but I wonder if any technical boffins can give me some more pointers.
Car is a UK Legacy 1990 1.8ECO (single point fuel injection)
Its slow to warm up, despite a new thermostat, and whilst driveable, power delivery is hesitant and somewhat jerky, especially at low RPM. When warm, dipping the clutch at junctions makes the engine fast idle at just over 2000rpm for a few seconds then it drops back to just under 1000rpm (not everytime, but mostly). Fuel economy is dire (i.e. about the same as my Audi S4 which would mean about 270miles to a full tank). Power at the top end seems to be reasonable (or as much as you can expect for a 1.8 in a legacy estate).
Routine maintainence done - filters, plugs, oil etc. New thermostat about 2 months ago. 119,000 miles.
Dealer unhelpful as this car is a beater that I use to move bikes in, so I'm reluctant to spend more than its value getting the dealer to sort it! Haven't had access to the diagnostic equipment, but wonder if this would be helpful (i.e. in a similar way to VAG-COM on Audis)
Any thoughts greatly appreciated.
Thanks
David.