i have a volvo 1999 s80 t6. car starts up fine but wont go over 20mph even i i floor the gas pedal. after letting it warm up for awhile , sometimes and hour or more, it will go about 30mph. sometimes the car will suddenly "catch" and then will run at normal speeds as if nothing was wrong w...

at first he car stuttered when first started up. after it warmed up it was fine. then it stuttered and wouldnt go ver 20-25mph while driving until after about 10 minutes of driving, then all of a sudden it wa fine and i got speed. now it doesnt go over like 25mph no matter what or how long its been ...