Mine used to run at about the same mpg, pretty much exactly the same! And I never smelt any excessive fumes or anything but changed the lambda sensor and started getting around 35 mpg.
The old one was black as anything, no wonder it wasn't working! Might be worth a look.
Also, the cold start valve / fifth injector stick open aparently. You just need to warm the engine up, pop it out and plug the hole then turn the engine back on, it shouldn't release any fuel when warm.
Hope that helps
