I have a similar prob with a 98 Ranger 2.5. Started out with misfire code on 2&4. changed plugs, changed both coils, changed IAC, TPS ,egr, fuel pump and all filters, 3 cans starting fluid checking for leaks, Will Idle at start up and evens out when warmed up. If driven down road will get to 50 or 55 in third gear but drops off severly in 4th with pedal on floor. Come to stop and dies. Hard to restart. $500.00 in parts this week and still stumped. I am at witts end.