[Paccool]

Hmmm, not sure but it may be due to you not having a throttle position sensor. what kind of tranny was behind the 4BT in it's previous life?

Does the tranny shift into OD ok and just won't downshift?

 

[Paccool]

The reason I asked about the TPS is I changed out the TPS with a potentiometer on the dash and mine doesn't want to shift down as fast either. I manually shift it down if I want it to kick in faster. I can control where it shifts up at but it doesn't like the downshift part.

The TPS was mounted on the top of the injection pumps. 91.5 is when the intercooled trucks came out and they had the 518 tranny.

 

[Paccool]

Are you sure the tranny has the right dip stick in it? If it is stock, do you know how many pints of fluid you put in it.

If it is foaming, are you sure there is no water in the fluid?

What kind of cooler do you have up front? Does the 4B have the water to fluid cooler on the passenger side of the block?

Where are you taking the tranny temp at? in the hot line going to the cooler or in the pan? If in the pan, I have been told the hot line temps are about 60 degrees higher. I can't say for sure but was told that. My temp gauge is in the pan and I am usually in the 130-160 range I try to keep it below 190 when towing and have Amsoil in it so it doesn't break down as bad when/if it gets hot.