Cylinder 4 misfire code

[feedthechicken]

I took my truck into the shop because it was idling rough and the check engine light would blink from time to time. The error code we received was that cylinder 4 was mis-firing, so we replaced the spark plugs and wires. Still getting the same message, the mechanic suggested that it was likely the computer had gone bad (or had a loose lead at the harness), and should be replaced. We have now replaced the computer, and after a week and a half of no problems, I am idling rough again (below 750rpm) and when the check engine light starts to blink the truck has a very hard time accelerating. I had originally thought it was sensor related or transmission problems, but I will admit I have not worked on too many Rangers before.

Does anybody have suggestions of where to look next?

 

[betomonroy]

I deffinitely doubt You have a problem with your computer. But if your computer is bad again You have to find out why.
I sugest You also check for a bad injector or a CMP (Cam Possition sensor) or CKP (Crank Position Sensor) as well as a bad Coil Pack.