I have a 1999 blazer the head gasket was blown so it sat for almost a year i finaly got the chance to replace it as well i changed plugs wires cap rotor fuel filter new battery as well now i can get it to start and so long as i keep the rpms up it sounds good but soon as i let it idle well soon as i let off the gas it dies and is real hard to get it started again i did a fuel pressure test it seems to be good im stumped can anyone help

 

Do you have a vacuum leak? Any hoses not attached?