I have an 04 Mach 1 with an Automatic. I have less then 15,000 mi on it, it is stored for approx 4-5 months during the winter. I had the tranny flushed last year and I am still have a surging sensation or it seems to be searching for gears at highway speed while you leave of the gas and coast. The best example is when your coasting on level or slight up hill, the tach bounces around like its down shifting then up shifting every couple of seconds. Anyone else know whats wrong or have had the same problems?

 

I had an automatic Mach for a while, but never had that issue. Kind of sounds like either the solenoids or maybe the converter. Have you talked to any transmission techs about it?

 

that's very very odd, admittedly im not as familiar with the 4r series as i am the C4/C5/C6 transmissions.
did they fill the trans back up? possible overfilling? could be the converter as well.

 

I talked to a few mechanics about it. No one knows what is wrong. The only thing everyone seems to think the problem is that it sits over the winter and it may be causing the tranny oil to become sticky and causing intermittent problems with solenoids ect.

 

worth checking out, im still looking for stuff about it.