Gas mileage

[gt6493c@prism.gatech.EDU]

Does anyone out there have a 2226cc 5 matched to the close ratio manual
Audi started using in '85?  If so, I was wondering what kind of gas
mileage you get, and what RPMs you are turning @ 55mph.  
Right now I am getting lousy highway mileage, well under 25 mpg
(EPA ratings for highway, '85 Coupe GT), and just over 19 mpg city
with conservative driving.
If anyone has any ideas as to a possible soure, I need some ideas.
Over Christmas break I replaced the hydraulic lifters and the fuel
injectors and had it tuned up to pass the emission inspection in South
Florida.  I figured that should fix the low gas mileage problem.
It seemed to have helped the city, but hurt the highway.  
I bought the car used a year ago, so I can't compare the mileage to when
the car was new.  I appreciate the help.
Thanks,
Eric