Volvo Repair: car starting but will not run, 2000 volvo s70, volvo s70

Question
I have a 2000 Volvo S70 (non-turbo) with 158,000 miles my car will got through the start cycle but when the rpm's drop back down it doesn't stop at 900 and just dies it does not always even do this sometimes it just cranks away,sometimes after a wait it will crank and run fine, what could be the problem and possible fixes? Disconnecting the battery to reset the computer has been mentioned along with the key sensor and a possibility of a fuel filter clogged up.

Answer
well the long cranking will happen if the car starts and dies and you try to start it again without turning the key off for a second then back on.I am not sure if this is what you mean by it just cranks I just thought I would mention this because sometimes this happens and people look at it as a problem but it is normal to do this.

as for the stalling it could be a bad electronic throttle module they go bad often.it could be a clogged fuel filter you would need to check fuel pressure with a guage and monitor it when it stalls.you could try cleaning the throttle module with a carb. or throttle cleaner and see if  it helps.