I have a 2001 F150 Supercrew 4x4, 4.6 175K miles that has some strange stuff going on that has a lot of people scratching their heads.

After towing a boat with OD off I exited the highway, upon taking off at a traffic light the transmission shifted back and forth between gears until I powered through it.

From then on the transmission felt like the torque converter wasn't unlocking/locking. At a normal take off the transmission seemed to shift way to early, and downshift way to late, to the point of almost killing the engine. Since then I have: installed an alternator, a set of MSD coils, TCC solenoid, shift solenoid, transmission filter.

There are NO codes, I took it to a reputable transmission shop. They didn't find anything wrong with the transmission, thought it may be an engine issue.

The truck idles great with no misses, if I take off with more power it goes through gears fine, good on the highway except for downshifting up hills, it downshifts hard.

 

throttle position sensor?

D

 

Just tested it and it tests good.

 

Since last post I have taken it to another trans shop, who said it was an engine issue, possibly fuel. I replaced the fuel filter after a couple tanks wit additives, MLP/Neutral Safety switch, battery, cables, alternator, PCM.
It still shifts too soon on take off and downshifts too late when stopping.

 

Since these basically shift off of throttle position and vehicle speed, It's most likely the computer getting info from either the TPS or VSS that isn't accurate to reality.

Or, it could have a different tire size or gear ration swapped in that the computer hasn't been told about.

 

I apologize for the delayed response, for thirty five bucks I will try a tps.
Thanks