ok, last week I had some issues with my 2003 Windstar cylinder 3 and 6 misfiring and tie rods (separate issue). Had the work done by my mechanic. Now the cylinder 6 misfire is back but only when the AC is off. If I turn off AC it comes back and light engine light comes on. If i drive it for a bit with AC on it doesn't happen. I have called my shop back they want me to bring it back. If this is something I can fix myself, I will do it. Any help would be great.

 

It would be helpful to know the milage on the vehicle, what exactly has be done to it by the mechanic ("work" is too general), and what the digital trouble codes are.

 

they cleaned the carbon deposits from the egr valve and plenums and replaced the inner tie rods. 3 months ago I replaced the coil pack due to misfire on 3 and 6. It had a tune up; plugs, wire and fuel filter. 8 months before that. vehicle has 157,000 miles. code is p0306

 

I think bluewind brought up a very good point.
A lot of things can happen in 8 months especially if a lot of hard miles were put on the vehicle.
Your post is somewhat confusing. Do you think you could go over it again and clarify ,in detail, exactly what is taking place?
We have learned some the hard way and some by others mistakes , as an example
the coil that was replaced , if it came from the land of chow mein 3 months is about right.
It does sound like there may be a ground problem, but to speculate without sufficient info would not be wise. Can you help us out here?

 

Have it scanned!

When they worked on the intake did they replace the isolator bolt grommets? (check the invoice)