I have a 1996 f250 7.5L I have what seems to be an intermittant misfire, it lasts about 5-10 seconds and then the check engine light comes on. The truck will run fine for several miles then all of a sudden it will reapear. The code is 173 right hego always rich. I have cleared the code twice but this keeps coming back. Is the miss causing the code or is the code causing the miss?

 

I had the same problem on my 95 F150 with the 5.0L engine just last week.My scanner showed code 173 also and said my O2 sensor wasn't switching from rich to lean.It did this after I drove a few miles and the engine warmed up.I replaced the sensor and the problem went away.