I have a 1992 Ford F2 50 with 460 I'm getting intermittent rough idle and bad gas mileage the truck has plenty of power and runs decent at high rpm but it has a slight miss at low RPM I would think that it's the ignition timing being a little off for a vacuum leak I took some starter fluid and sprayed all around the hood to and all over the hoses but notice no change in RPM the truck has a new distributor cap and rotor as well as new spark plugs and wires and an O2 sensor I did a vacuum test and it's holding very steady at 18 inches high did a compression test and all cylinders are between 150 and 155 I'm not sure what else I can do besides start replacing things which I don't like to do but this truck is all computer-controlled and I can't even change the ignition timing or even tested does anyone have any ideas on what I can look for to take care of this it just has a very slight miss at Idle and it gets bad gas mileage on the freeway which might be it in part due to the bad will alignment which I'm going to get fixed budwin uns standing by the exhaust it's like I hear little backfires in there maybe like the ignition timing is off but this is EFi