L300 auto transmission not gearing down uphills..

[surferboy]

Hello all, I have not been here in ages! I have a question concerning my L300 Automatic transmission.
It seems that the van shifts up normally and then if going uphill, instead of gearing down to keep the momentum and power going, it appears to shift up a gear so now stuck at 1,200 RPM's up hill doing barely 40 km's/hr! this is recent and I barely made it to the west coast with my van loaded with all camping gear and one passenger. I can manually put the van in second and first gear which tells me that my transmission still works.
If I lift my foot off the gas and push back down nothing happends, the only thing that seems to help is taking the Over drive off which allows the tranny to gear down and start reving at an appropriate RPM.
It is now doing this intermittently, very annoying as these vans are already under powered for weight and size of vehicle and is a slow crawl uphills.
I remember a few years back someone mentioning a similar problem on here, something to do with a cable adjustment.
If anyone has good information with some pictures of cable adjustment procedures that would be fantastic.
Thanks anyone for any help at all.
Cheers!

[Growlerbearnz]

Have a look at your injection pump- the cable that controls the transmission has an orange dust boot. It should be connected to the throttle linkage, but I'm guessing yours has become disconnected. It should be fairly clear where it connects.