On my '93 I have a E4OD that i swapped in instead of the ZF5. The auto has 5,000 mi. on a complete rebuild and heavy duty update(all the goodies). I have the FLPS set right. the trans shifts solid when unloaded (my wife says rough but she does know what a good truck trans shifts like). but when I load it up it shifts PERFECT. so my question is if i plug in the intercepor is it going to make the unloaded shift worse.

 

Probably will make unloaded shifts more harsh. There is a happy medium for how hard an auto should grab the next gear. Too bangy and you might save slight amounts of (likely insignificant) wear on the clutches and maybe a tiny bit of reduced heat, but the hard parts will take a hammering along with your differential gears, drive shaft and U joints.

The fact that if "feels" perfect when loaded could also be the effect of the truck being anchored by the extra mass that the momentum of the rotating parts (shafts, engine crank, torque converter, flywhee, etc) have to pull against when the change happens. It could very well be the actual shift event is happening in nearly an identical amount of time, just that the truck is held back too much by the added weight, to feel the smack in the backrest of the seat.

If all that sounds like what is happening, then I wouldn't change a thing because it means the tranny is set up perfectly just the way it is.

 

that is exactly what its doing. I will let it be. I have another question. The transmission is making a hissing noise when in Neutral and Park idling. if you rev it slightly it goes away. It very quiet just barely noticable with the motor running. also seems more when at operating temp.