Rebuilt 97 4.2 automatic runs well at speed. At idle there tends to be shudder surge when in gear. If the truck is in neutral, the idle is still a bit rough just not as noticeable.

Just rebuilt. New lower half including bearings and pistons. New Plugs, new wires, new coil pack, new fuel filter.

I think I have an injector issue or O2 senor problem. The old engine lower intake gasket failed leading to several bent rods but it didn't have this idle problem. As I mentioned, runs great at speed. No more FORDs. Ideas?

 

Try cleaning your IAC valve.Also,clean the throttle body.Use only throttle body cleaner on it! One more item to clean is the MAF sensor. Remember to disconnect the negative battery cable while doing these procedures.

 

Where is the IAC located and does this engine have a PCV?

The links on this web site about related articles return you to the forum page, so you have to read them all vice the specific article you wish to see, annoying!

 

The IAC valve is on the very top of the intake manifold,rite behind the throttle body.It has 2 screws holding it to the manifold and a electrical connecter to the solenoid part.. The pcv valve is on the passenger side valve cover all the way to the rear. While your at it check all your pcv lines to and from the valve,esp. the 90* elbow at the manifold. They usually get holes in them.

 

First, thanks for all the info on this subject. It was much appreciated.

I checked the PCV valve and it was clean, looked new. I removed the IAC and it too looked new. I reused the same gasket it was so new. Truck runs the same, rough idle, mushy gas pedal off the line. The rebuilders did a great job of house keeping, there's no dirt anywhere. In fact they cleaned and painted everything they reused. I tried to inspect as many vacuum lines as I could, no damage found. Aw well.