I have a 98 S70 turbo I have replaced Engine coolant sensor. distrubutor, plugs and wires also fuel pump and filter, cam and crank sensor and still only starts intermitedly and when it does it backfires and runs very rough and wont idle and every once in a blue moon will start and run fine and there is no check engine lights

 

why did you replace all that stuff?

Sounds you should ck your fuel pressure..

 

Schundle, did you also check the fuel pump relay? The contacts can get corroded enough where it will fire up the fuel pump, but not pass enough current to keep the pressure correct.