Will a tune-up fix this (idle going up & down)?
I'm an admitted newbie to tune-ups so here goes...
Bought a '97 XLT a year ago with the 4.0L V6. Didn't need to do a whole lot of anything to it except filter changes when I bought it. Has run fine all this time and have been getting decent gas mileage (btwn 19-20mpg hwy).
Within the past two months, it's started to run rougher. The idle goes from around 2500rpm to nearly dying. Gas mileage is down below 17mpg hwy now.
Was going to change plugs, wires but is there something else I need to look at as well? O2 sensors? Air filter still looks real good, but should I think about changing it as well?