I have a 2005 Crown Vic P71. My transmission shutters between 3rd and over drive. If I hit the gas it kicks down and stops until back in over drive I'm try to figure out what transmition this is. What I have found on the Internet is running me in circles. One site says there are 12 different versions and another says their is only one I was told I could identify it by the VIN # But I don't have that . I did a full chassis swap with a 65 F100. When I scraped the body I had to give the title I'm going over my options as to maybe repair myself or have it rebuilt Any help would be awesome

 

Welcome to the site..

Would be a 4R75E. How many miles on the unit?

Sounds like your condition is torque converter shudder. The converter clutch slipping on the OD lockup.
when was the last time the fluid was changed? Sometimes a fluid change will correct the condition, or lessen the shudder if higher mileage..

 

Unsure if the fluid has been changed. It has 130k on it. I’ll give that a try. I was using as my daily driver but it’s getting worse and it’s super annoying. I did put shutter stop in it, like magic it worked great for three or four days.

 

When it acts up hit the OD off button and see if it kicks down correctly. Without me seeing it, I'd bet your OD band is going south.

Also a fluid change more than likely won't do anything. That's a PM. Once the damage is done, It's done. I've done loads of trans flushes, and customers think it will magically fix the problem. You can try some Lucas Trans Stop Slip. If it's not too far gone, it can help, but no guarantees.

 

I would turn the over drive off and it would work great. I did the fluid change with no signs of change directly after. But the more I drove it the better it got. Now months later is working great with no issues. I usually see other people do the easy stuff and it fixes it. This is a first for me. I’m guessing the car sat before I bought it and it needed to be driven to get all the parts moving like their supposed to.