My ed fairmont 6cyl has spark and fuel at the rail but won't start once in a while it'll start with a lot of coaxing but won't rev it splutters and coughs then dies. It had been running fine until today we were driving along and it started loosing power and back fired loudly, it couldn't be driven over 1/4 throttle then cut out all together. I've check spark and and fuel at the rail both of which it has.i checked the injectors with the old screw driver on them to the ear check and no clicking was present on cranking.
I'm at a loss, any suggestions?