Long story short, kid came home from college and the truck was running real bad... 99 Ranger 4.0L 4x4 137000 miles.... Missing, hesitating, and would not go over 50mph... Ran the codes, misfire on cyl 3 and 4... put in new plugs, cleaned MAF and IAC... ran a tad better but codes still show misfire on cyl 3 and 4... replaced the plug wires... runs about the same, real bad and will not go fast... put in a new coil... still running bad and will not go over 50.... same codes... replaced injectors on cyl 3 and 4... runs a tad better.. still bad but better... not throwing any codes but only drove it for 4-5 miles... driving the truck is like you are pulling a huge anchor... you put the gas pedal to the floor and the truck gradually picks up speed... does not want to shift though.. if you lift your foot a little, then it shifts... and eventually you top out at 48-49 mph... any help in diagnosing this will be greatly appreciated..