engine started being real sluggish mechanic said that engine may be junk but is gonna look at fuel injectors could my motor be junk iof its not the fuel injectors he said it is misfiring the 1 and 3 cylinder i think and that he heard noises in th motor or something thats why he was gonna look at the injectors i been reading alot and it all points to injectors he said there is plenty of spark on the outside of the motor any suggestions