Okay so here is something I have not been able to find here. I have a 1997 F150 4 x 4 with the 5.4 overdrive transmission. When I accelerate from a stop I can feel the slip of the transmission until I reach exactly 35 miles an hour. Above 35 seems to be normal and have plenty of torque.
The funny thing about this is I have had a 2001 Windstar same 35 miles an hour. I have also owned a 1997 Ford Explorer with this exact same issue. Three different motor and trans combination that will not lock up until you reach 35 miles an hour.
The truck has 213,000 I have replaced all coils fuel filters catalytic converter and torque converter. Have exterior tranny cooler. engine runs good and strong. And no code I have a reader.

Anyone have any ideas

 

The torque converter clutch will lock up at about 35 MPH. Below that there are several hundred RPM slip in the torque converter. That's how an automatic transmission operates.

 

I believe the slippage is to much. 2000 3000 going up hills. When it hit 35 it drops 2 or 3 thousand. And won't break loose again until you let off on the throttle and Coast

 

Can't be 2000 to 3000 rpm.
You must mean 200 to 300 RPM which is normal convertor fluid shear slippage in an unlocked converter.
If you see it in other vehicles, you have the wrong idea of how it works.
You can see the slippage by watching the Tack.
As soon as lockup occurs the Tack stops reacting to throttle changes over a wide RPM.
This is normal operation.
Suggest you have another truck owner with the same show you.
Also if your cruising along and suddenly lift the throttle and reapply, the tack should show you the converter unlocked then locked again within a few seconds . That is also normal. That's the PCM program doing that.
Good luck.

 

I have worked on vehicles most of my life I am 52 years old I fully understand how torque converters work. It will drop from 3500 RPMs to 1600 at 35 miles an hour. Under 35 miles an hour I can bounce the tack with the throttle as if it was in neutral. After it has completely locked up the tack does not jump tax should run the same as speedometer in second and third gears. I uunderstandin lower gears the tack will not respond with the spedometer because of gear ratios I have owned several other vehicles over the years and only the Fords slip that bad below lock up. The older C4 and C6 is if you jump on even before torque converter has locked you still can feel the acceleration. This one doesn't go below 35

 

C4 and C6 did not have a lockup torque converter, so they NEVER locked.

 

Its a waist of time with this guy.
He comes with a faulty thinking then will not hear the way it is on these electric controlled transmissions..
Only way big RPM jumps take place is with large downshifts that skip a gear or the trans has a fault.
Absolutely right, the C4 and C6 vacuum/centrifugal governor controlled transmissions never had any kind of lock up.
They ran is slip mode all the time and produced a lot of heat..
Sorry if you feel insulted but that's the way it goes.
Ova and Aut as they say on the two way radidio.