have a 1999 blazer 106,000 miles new rotor, wires, plugs, new rebuild engine but i cant get above 10-12 mpg does anybody else get bad gas mileage? I have never got good mileage with this vechile when i bought it i thought it would do about 20 mpg not 10-12 anything i can do to make it better?

This works for me.
Set the tire pressures to 32psi front & 30psi rear.
Take all unnecessary weight out of the car.
Drive the speed limit.
On level ground on most streets, take your foot off the gas pedal 100 yards before you stop...try to coast to a stop, it will make the brakes last a long time too.

You say you have a "new rebuilt" engine...how many miles on it? An engine that's still in the break-in period will always get worse gas mileage....

what do you usually average when you do this method?

After seeing numbers from many Blazer owners, i'd say the Blazer averages 13-17 mpg in the city, 20-23 on the highway, and 16-19 with a mix of both driving conditions. A tranny and differential fluid change helps gas mileage also.

Yep, 16 to 18 in my '92.