[blah]

hmmm sounds odd, my car will just coast for ever, even on slight hills ill gain 5-10 mph. and thats when i let off the gas

 

[blah]

my car(auto) did that until i got my injectors clean out with the GM top flight injector cleaner(or somthing like that). now when coasting down hills in D4 itll gain serious speed

 

[blah]

just go to the GM parts department and ask for injector cleaner. theyll point you in the right direction

 

[blah]

well the injector stuff i used was the stuff they blast into the intake(you need to replace your pcv valve afterwards usually)

 

[blah]

well i had the fuel filter done also but that was after the injectors were done. and right after the injectors were done, i would coast really well