Picked up a new van/RV recently, trying to work out why I dont get high gear or lockup.
looking at my linkage -
I don't think my linkage setup for kickdown is setup correctly, I don't think the spring there should be pulling the kick linkage forward.
I believe the pin should be in the middle of the slide. I think this might be holding the transmission in a permanent partial kick down and may be why I don't get 4th gear out of it.
This also brings into question the whole adjustment for all of the TBI.

Can anyone show me or direct me to something to help me get this back the way it should be?

 

The kickdown linkage and spring are setup correctly.

 

I find that hard to believe, the whole purpose of the slot is to allow for some throttle to be applied before the kick down moves, as it is now, the kickdown moves at any amount of throttle, no play.
So I think its in a kick down state even at idle.

I did find a diagram that shows everything is in the right place, but I still think its not adjusted correctly down on the transmission end.

 

Spring #9 is right there in your diagram connected to the same stem as the throttle return spring, while the other end is connected to the bracket #1 passes through, just like the setup shown in the picture you posted. So yes the spring belongs right where it is, and yes the linkage is supposed to move with the throttle. The purpose of the slot in the kickdown linkage is so if the kickdown linkage get stuck or moves slow it won't hold the throttle back from closing.

If you still think the linkage is related to your shift issue, then it's possible it's adjusted too tight. To quickly test for this, disconnect the linkage from the throttle, tie it towards the firewall, and go for a drive to see if anything changes. If it doesn't you have a transmission issue. If it does then adjust the kickdown linkage.

 

Gotta be an adjustment procedure for that somewhere out on the web.... Youtube video??