I've got a 2002 Ranger 3.0 V6 with 250k miles on it. I have had 6 or 7 misfires with this truck over the last 10 yrs or so. So I know exactly what it feels like. My truck has been running real rough lately. It feels like a misfire, but only at idle. And when accelerating in 1st gear sometimes. I had an auto parts store run a diagnostic but all 6 cylinders are running fine. (no misses) I have replaced the fuel filter. I have run a few Lucas fuel treatments through it. But it's still running real rough at idle. If it's not a misfire... what could be the problem. Could the A/C compressor or one of the other pulleys attached to the belt cause it to jitter and shake? What could cause something that feels like a misfire when all 6 cylinders are running fine? Let me know what to check next... Thanks!

 

Welcome to the forum

I had a failing Fan Clutch that acted like that, engine vibration without misfires, it would get out of balance then back in balance

Give the fan a wiggle see if its tight