Poor gas mileage on 94 pontiac v6

94 Pont Grand Am only getting 18mpg. Tuned up, EGR and injectors cleaned, Catalytic backflow check ok. Any ideas on poor mileage?

How about some more information. How long have you owned the car? Has the mileage changed? What kind of mileage was it you getting and what are you expecting. Auto or manual transmission? Are there any derivability issues? has the driving changed (different route to work), different fuel, Has the mileage changed with the seasons? New driver (like 16 year old boy?)

The V6 average (city driving) is approx. 20mpg.

Any mods done to the vehicle?

Thanks for reply. Ive owned the car for 5 years. 211,000 miles now. Mileage was previously 24ish city, 27hwy, would expect to maintain that. Now getting approx 19 all the time. Auto trans. No driving changes or fuel changes. Summer in Kansas but mileage dropped in spring. I am 47yr old conservative driver, combo of city and hwy commute to work. Have since changed plugs, wires, air filter, fuel filter. Shop ran OBd1 computer check with error code 77. Shop then did upper engine/egr/injector clean. Also said catalytic convertor and backpressure check was ok. Tire pressure at 30psi.

Tuen up with plugs, wires, air fileter, fuel filter, injector/egr clean, but no major modifications