1997 ford ranger 4.0L acts like its is eather skipping or misfiring. when i press the gas petal in nutral it seems to run smooth but when i am going down the road the truck acts like it is misfiring or something. it is a 5sp with a new clutch so i dont think the clutch is slipping but i need to get this fixed. after a few minuts of running it will quit doing it